What Independent Travel Really Means
Independent travel is a hydraulic control mode found in many modern excavators, particularly in models like the Kobelco SK120-III. This feature allows the machine to move while simultaneously operating attachments—such as the boom, arm, or bucket—without either function compromising the other’s speed or responsiveness. In standard operation, hydraulic pumps are shared across travel and implement circuits, which can lead to sluggish movement when both systems are engaged. Independent travel solves this by splitting pump flow: one pump is dedicated to travel, while the other handles attachment functions.
Hydraulic System Architecture Behind the Feature
Excavators typically use a dual-pump hydraulic system. In normal mode, both pumps combine flow to whichever function demands it most. When independent travel is activated, the system reroutes one pump exclusively to the travel motors, ensuring consistent track speed. The second pump continues to power the implement circuits. This separation prevents the common issue where digging or lifting causes the machine to slow down or stall during movement.
This mode is especially useful in trenching operations, where the operator needs to reposition the machine while keeping the bucket engaged with the ground. Without independent travel, the machine might hesitate or jerk, reducing precision and efficiency.
Activation and Control Interface
On machines like the SK120-III, independent travel is typically activated through the mode selector switch, often located near the operator’s right-hand console. It may be labeled as “travel mode,” “priority mode,” or simply part of the work mode selector. There is usually no standalone toggle switch; instead, it’s embedded within the machine’s operating logic.
Operators should consult the machine’s service manual to confirm activation procedures, as some models require the engine to be at idle or the travel levers to be neutral before switching modes.
Field Applications and Operator Feedback
In pipeline construction, operators often praise independent travel for its ability to maintain smooth movement while dragging pipe or trench boxes. One veteran operator in Pennsylvania recalled a job where his Kobelco excavator had to reposition every few feet while laying conduit. With independent travel engaged, he could keep the bucket aligned and avoid re-digging sections due to misalignment.
Similarly, in forestry applications, machines equipped with grapples benefit from this mode when moving logs while rotating or adjusting the grapple. It reduces the need to stop and reposition, saving time and fuel.
Maintenance and Diagnostic Considerations
If independent travel is not functioning properly, common issues include:

• Faulty mode selector switch or wiring
  
• Hydraulic pump imbalance or wear
  
• Blocked or leaking pilot lines
  
• Software calibration errors in electronically controlled systems
  

Understanding The Cat 320D Undercarriage Configuration
The Cat 320D is one of Caterpillar’s most widely used 20–22 ton class excavators, often working in quarrying, construction, and utility projects worldwide. Like all crawler machines, its undercarriage configuration directly affects traction, stability, and component life.
A key parameter in that configuration is the number of track links (also called chain links or pads), which determines overall track length and how the chain wraps around the sprockets, rollers, and idlers.
On a standard Cat 320D (non–long undercarriage), the factory configuration uses:

• 45 links per side
  
• Standard track gauge and pitch suitable for the 320D frame
  
• Track groups designed and supplied as a complete assembly from Caterpillar
  

• 49 links per side
  
• A longer track frame and more ground contact area
  

• Increased ground contact length
  
• Better stability on slopes or when lifting heavy loads at reach
  
• Slightly different load distribution and wear pattern
  

• Standard Cat 320D → 45-link track chains
  
• Cat 320DL (long UC) → 49-link track chains
  

• The workshop counts 45 pads on the existing chain.
  
• A supplier insists the machine “should” have 49 pads.
  
• The local dealer offers a 49-link track group and proposes to “take a few out” to make it fit.
  

• Physically count the links on each side.
  
• Confirm the serial number and exact model (e.g. Cat 320D vs 320DL).
  
• Check the undercarriage frame length visually and, if possible, by measurement.
  

• Two complete track groups (one per side), each consisting of:
  • One assembled link chain (track chain assembly)
    
  • 45 track shoes (pads)
    
  • Bolts and nuts in matching quantities for the shoes
    

• Undercarriage geometry (distance between idler and sprocket centers, roller spacing, etc.) is designed for a specific pitch and link count.
  
• Deviating too far from that can cause accelerated wear or even derailment of the track.
  

• 7.5 inches (approximately 190.5 mm)
  

• 190 mm (7.48 inches)
  

• 0.5 mm × 45 links ≈ 22.5 mm total difference
  
• Over 2 cm of cumulative error as the chain wraps around the sprocket and idler
  

• Poor tooth engagement on the sprocket
  
• Abnormal noise and vibration
  
• Accelerated wear of sprocket teeth and bushings
  
• Higher risk of derailment, especially under load or on uneven terrain
  

• Are the dimensions exact metric equivalents of the OEM imperial specs?
  
• Or are they independent metric designs approximating the OEM?
  

• Pin/bushing match and pre-load
  The chain is assembled with a specific pin and bushing interference and twist to match wear patterns and bending loads. Cutting out links and rejoining must be done with proper tooling and technique; otherwise you can weaken the joint.
  
• Symmetry of the chain
  Removing the wrong number of links from one side or in the wrong position can affect how the track stretches and runs over rollers.
  
• Tensioning range
  If the assembled length is slightly off due to non-OEM pitch, the track adjuster may end up fully extended or fully retracted to get tension “close,” leaving no adjustment room as things wear.
  

• Use correct-spec OEM or high-quality aftermarket chains
  
• Avoid “Frankenstein” assemblies built from mismatched components
  

• Hobby / occasional use
  • Lower annual hours
    
  • Undercarriage wear is relatively slow
    
  • Affordable aftermarket components may be acceptable, even if life is shorter
    
• Production / commercial use
  • High annual hours (1,500–2,000+ hours per year is common)
    
  • Undercarriage can constitute 50% or more of lifetime maintenance cost
    
  • Higher upfront cost for OEM or premium aftermarket parts often pays off in:
    • Longer service life
      
    • Fewer breakdowns
      
    • Less downtime and labor
      

• Confirm model and configuration
  • Verify: 320D vs 320DL
    
  • Check the serial number prefix and build configuration
    
• Count the existing links on the machine
  • Count pads/links on each side at least twice
    
  • Standard 320D will typically show 45 links
    
• Measure key dimensions on the current chain
  • Pitch (center-to-center of pins)
    
  • Bushing outside diameter (where it meshes with the sprocket)
    
  • Shoe width (e.g. 600 mm, 700 mm, etc.)
    
• Ask the parts supplier detailed questions
  • Exact pitch (in both metric and inches)
    
  • Whether their specs match Caterpillar’s imperial dimensions precisely
    
  • Whether the chain is compatible with Cat 320D sprockets without modification
    
• Decide your quality tier
  • OEM Cat track groups
    
  • Premium aftermarket with proven reputation
    
  • Economy brands for light-use machines
    

• 190 mm pitch
  
• 49-link chain for “20-ton excavators” in general
  

• The sprockets developed sharp hooking on the teeth
  
• The tracks started jumping under heavy digging
  
• Re-tensioning became a weekly chore
  

• Balance durability and fuel efficiency
  
• Standardize track components where possible
  
• Offer variants (like long undercarriages) for specific markets and applications
  

• OEM spares
  
• Multiple tiers of aftermarket suppliers
  
• Rebuild and re-bush services for chains and rollers
  

• Treat 45 links as the reference for a standard Cat 320D undercarriage.
  
• Remember 49 links typically indicates a long undercarriage variant (320DL or similar).
  
• Always confirm the model suffix and serial number before ordering.
  
• Verify track pitch against OEM specs; avoid chains with approximate dimensions if you expect heavy use.
  
• Prefer OEM or high-quality aftermarket chains for production machines.
  
• If a supplier suggests using a 49-link group and “just taking some out,” ask for:
  • Evidence of successful installations on the same model
    
  • Clear statement of pitch and compatibility with Cat sprockets
    

The CAT D3 and Its Cooling System Design
The Caterpillar D3 crawler dozer, introduced in the late 1970s, was designed as a compact yet powerful machine for grading, clearing, and light earthmoving. Built by Caterpillar Inc., a company with a century-long legacy in heavy equipment, the D3 featured a torque converter transmission and a radiator-integrated transmission cooler. This design allowed the transmission fluid to be cooled via the same airflow and coolant system used for the engine, simplifying the layout but introducing vulnerability when the cooler fails.
In early models like the 1980 D3, the transmission cooler was embedded in the lower section of the radiator, functioning as a heat exchanger. This setup was efficient but difficult to service, and when internal leaks or blockages occurred, symptoms could be subtle until major damage surfaced.
Signs of Cooler Failure and Fluid Contamination
One of the most telling signs of cooler failure is the presence of milky fluid during maintenance—often discovered when removing components like the starter. Milky transmission fluid typically indicates water or coolant contamination, which can result from a breach in the cooler’s internal passages. This contamination compromises lubrication, increases friction, and can lead to clutch pack degradation or torque converter overheating.
Operators may also notice:

• Sluggish gear engagement
  
• Transmission overheating under load
  
• Discolored or foamy fluid in the reservoir
  
• Unusual noises during shifting
  

• Ensure it’s rated for transmission fluid and compatible with the D3’s flow rate
  
• Mount it in a location with adequate airflow, ideally near the radiator fan
  
• Use high-temperature hydraulic hoses and secure fittings
  
• Monitor transmission temperature with a gauge to confirm effectiveness
  

• Change transmission fluid every 500 hours or annually
  
• Inspect fluid color and consistency monthly
  
• Flush the radiator and cooler passages with non-corrosive cleaners like Cascade
  
• Install a temperature gauge if not factory-equipped
  
• Avoid prolonged high-RPM operation without load
  

Why Old Paper Manuals Still Matter
In the age of digital PDFs and online parts lookup, a thick stack of paper service and parts manuals can look outdated. Yet for many owners of older backhoe loaders such as the Caterpillar 426B, these manuals are still one of the most valuable “attachments” they can buy.
A complete lot of service and parts books for a 426B does more than tell you where the bolts go. It preserves factory knowledge, field-tested procedures, and accurate exploded views that were written when the machine was new. For a contractor trying to keep a 25- to 35-year-old backhoe profitable, that information can easily be worth more than the asking price of a used manual set.
On the market, a single OEM parts manual for a 426B commonly sells in the 60–90 USD range, and full sets that include service, operation and maintenance, and parts volumes can reach or exceed 200 USD depending on condition and rarity. For a buyer, paying something in that neighborhood for a complete lot is often cheaper than hunting down the books one by one.
The Caterpillar 426B In Context
The 426B is a conventional 4×2 or 4×4 backhoe loader produced by Caterpillar in the late 1980s and 1990s as part of its B-series line. While exact production numbers are not public, industry estimates suggest that tens of thousands of B-series backhoes (420B–436B family) were sold globally over their production life, many into North America and Latin America, with others going to Europe, Africa, and Asia through dealers and secondary markets.
Caterpillar itself dates back to the 1925 merger of Holt and Best, and has grown into one of the largest construction and mining equipment manufacturers in the world, with annual machine sales often over 40 billion USD in the last decade. In that context, the 426B is one small piece of a very large lineup—but for small contractors and farmers, it has been a core tool for trenching, loading, and light roadwork.
Many 426B machines in use today are over 25 years old. Their economic survival depends on two factors:

• The owner’s willingness to perform or manage maintenance economically
  
• The availability of accurate repair information and parts identification
  

• Operation and Maintenance Manual
  • Daily and periodic checks
    
  • Proper lubrication intervals and oil specifications
    
  • Safe operating practices and load limits
    
• Service (Workshop) Manual
  • Step-by-step procedures for disassembly and reassembly
    
  • Adjustment specs for hydraulic system, transmission, brakes, and axles
    
  • Diagnostic flowcharts for common failures
    
• Parts Catalog (Illustrated Parts List)
  • Exploded diagrams of every subsystem
    
  • Correct Caterpillar part numbers for each component
    
  • Serial-number ranges and configuration notes
    
• Sometimes supplemental bulletins or revisions
  • Updated torque specs
    
  • Superseded part numbers
    
  • Late-production changes
    

• Service Manual
  A technical book that explains how to repair and overhaul the machine. It includes disassembly procedures, special tool references, torque specifications, and troubleshooting charts.
  
• Parts Manual / Parts Catalog
  A catalog that shows every component in exploded diagrams and lists the correct part number, description, and quantity. It is used to order parts and to identify how assemblies fit together.
  
• ETC / “Etc.” In Listing
  In many sales descriptions “426B, etc, backhoe manuals” indicates that the lot may cover several closely related models (for example, 416B, 428B, or similar) in addition to the 426B, which increases the value for shops servicing more than one model.
  
• Serial Number Prefix
  Caterpillar uses a 3-letter or 3-digit machine prefix to identify a particular series or configuration. Correctly matching the manual’s serial number range with the machine is crucial.
  

• Workshop practicality
  Mechanics can leave a paper book open next to the machine, mark pages, and refer to diagrams without worrying about oil-stained laptops or dead batteries.
  
• Search reliability
  A physical parts catalog cannot “crash” or lose access when internet is down; for remote jobsites this matters.
  
• Completeness
  Some digital copies are incomplete or poorly scanned. A factory paper set often has clearer diagrams and all fold-outs intact.
  
• Resale value
  When selling a machine, including the original manual set can raise buyer confidence and slightly increase selling price. Anecdotally, small contractors report that a clean backhoe with manuals can sell 5–10 % faster and for several hundred dollars more than a similar machine without them.
  

• Engine power typically around 70–80 hp
  
• Operating weight near 7–8 tons depending on configuration
  
• Hydraulic system pressures often in the 2 500–3 000 psi range
  

• Mis-set relief valves, causing weak hydraulics or blown hoses
  
• Reassemble axles or brakes incorrectly, leading to unsafe operation
  
• Choose incorrect fluids that shorten component life
  

• Rebuilding a hydraulic pump incorrectly can cause early failure, with replacement costs commonly in the 2 000–4 000 USD range for reman units on older backhoes.
  
• Mis-adjusted clutches or shuttle transmissions can lead to premature wear, requiring expensive overhauls.
  

• Can pay for itself after one or two major repairs done in-house instead of sent to dealer
  
• Reduces diagnostic time because diagrams and system descriptions are immediately available
  
• Helps train new mechanics, who can learn correct systems layout instead of guessing
  

• He learns proper hydraulic test procedures
  
• Borrows a gauge set and runs pressure checks at specified ports
  
• Discovers the main relief valve is out of adjustment and a filter is badly restricted
  

• Physical condition
  • Pages complete, legible, and not soaked in oil
    
  • Binding intact enough for regular use
    
  • Fold-outs and wiring diagrams present
    
• Coverage
  • Correct serial number range for their machine
    
  • Includes both service and parts volumes, not just one or the other
    
  • Any supplements or later revisions
    
• Price vs. alternatives
  • Compare with individual manual prices and downloadable versions
    
  • Consider the cost of one mis-diagnosed repair as a benchmark
    

Understanding Chain Grades and Their Applications
Transport chains are classified by grade, which indicates their tensile strength and suitability for load-bearing tasks. The most commonly used grades in equipment hauling are:

• Grade 70 (G70): Also known as transport chain, it’s designed for load securement and meets Department of Transportation (DOT) standards.
  
• Grade 80 (G80) and Grade 100 (G100): These are alloy chains used for overhead lifting and heavy-duty applications. While stronger, they are not required for standard transport unless specified by local regulations or extreme conditions.
  

• 5/16-inch Grade 70 chain: WLL of approximately 4,700 lbs
  
• 3/8-inch Grade 70 chain: WLL of approximately 6,600 lbs
  

• Use long chains for flexibility in anchor points
  
• Keep short chains for securing attachments or auxiliary equipment
  
• Carry extra chains for unexpected loads or multi-point tie-downs
  

• Invest in Grade 70 3/8-inch chains with grab hooks for general transport
  
• Keep at least four chains on hand for flexibility and compliance
  
• Inspect chains regularly for wear, rust, and deformation
  
• Store chains in a dry, secure location to prevent corrosion
  
• Use ratchet binders or lever binders rated for the chain size
  

Understanding the Role of the Fuel Tank on a D5G
On a Caterpillar D5G 小型推土机 (track-type tractor), the diesel fuel tank is more than just a metal box holding fuel. It forms part of a tightly packaged rear structure that shares space with hydraulic components, electrical harnesses, and sometimes rear attachments like winches or rippers. A typical D5G fuel tank on Tier 3–Tier 4 era machines holds roughly 260–300 liters of diesel, enough for 8–12 hours of work at moderate load, so any removal procedure must respect both the volume of fuel and the surrounding components for safety.
Caterpillar designed these machines with rear-mounted tanks to keep the center of gravity low and close to the machine’s main frame. That improves stability on slopes and during heavy pushes, but it also means the fuel tank is tucked in behind guards and structural plates. When the time comes to remove the tank – for cleaning, rust repair, leak welding, or access to hidden components – the job is not as simple as on a small tractor or pickup.
In practice, tank removal on a D5G usually appears when you have internal contamination, water and sediment that routine draining can’t cure, or damage from years of vibration and corrosion. Before attempting removal, you need a clear plan, proper tooling, and a safe work area.
Typical Reasons to Remove a D5G Fuel Tank
Common situations that push owners and mechanics into a full tank removal include：

• Persistent fuel contamination problems
  • Repeated fuel filter plugging
    
  • Visible rust flakes or sludge in drained fuel
    
  • Chronic water accumulation despite regular draining
    
• Damage or leaks
  • Cracked welds from vibration
    
  • Tank rubbed thin where it contacts frame members
    
  • Impact damage from stumps, rocks, or debris
    
• Access to components hidden behind or above the tank
  • Rear hydraulic lines or valves
    
  • Rear harnesses or connectors
    
  • Modifications for fire-suppression tractors or auxiliary accessories
    
• Refurbishment of older machines
  • Repainting and cosmetic restoration
    
  • Internal coating to extend tank life
    
  • Replacement with an upgraded or remanufactured tank
    

• Park the machine on level, solid ground
  
• Shut down the engine and remove the key
  
• Allow hot engine and exhaust components to cool fully
  
• Engage parking brake and block the tracks if necessary
  
• Keep fire extinguisher within arm’s reach
  
• Wear fuel-resistant gloves and eye protection
  
• Prepare approved fuel containers for draining diesel
  
• Plan a disposal method for contaminated fuel and sludge according to local regulations
  

• Opening or removing rear access plates
  
• Removing protection panels or guards beneath and around the tank
  
• On machines equipped with winches or rear attachments, removing additional plates to reach drain valves and lower mounting brackets
  

• Slowly removing the fuel tank cap to relieve internal pressure
  
• Cleaning around the cap area to prevent dirt falling inside
  
• Locating the drain valve or plug under the center or rear of the tank
  
• Placing a suitable container under the drain outlet
  
• Opening the drain valve and allowing water and sediment to drain first
  
• Continuing the draining process until the fuel level is low enough for safe removal
  

• Label and disconnect fuel supply lines
  
• Label and disconnect return lines
  
• Disconnect any fuel level sender harnesses or auxiliary sensors
  
• Remove or detach vent and breather lines from the tank
  

• Always use a lifting device such as an overhead hoist, engine crane, or forklift
  
• Attach lifting slings to designated lifting lugs or strong structural points
  
• Support the tank before removing the final mounting bolts
  

• Loosening, but not fully removing, upper mounting bolts to keep alignment
  
• Removing lower mounting bolts and any stabilizing brackets
  
• Using the hoist to take the weight off the mounts
  
• Removing the remaining bolts and slowly lowering the tank out of the frame window
  

• Internal surfaces
  • Look for rust, pitting, and flaking
    
  • Check for sludge from degraded diesel and microbial growth（俗称“柴油泥”或“藻泥”）
    
• Weld seams and corners
  • Check for hairline cracks
    
  • Inspect previous repairs for quality
    
• Mounting flanges and brackets
  • Look for distortion from impacts or over-tightening
    
  • Confirm that rubber isolators or pads are still intact
    
• Fuel sender and pickup assemblies
  • Inspect strainers or screens
    
  • Check for broken floats or bent arms
    

• Hot detergent washing
  
• Steam cleaning
  
• Mechanical agitation with chains or media (for severe rust)
  
• Drying with warm air to avoid condensation
  

• Lift the cleaned or repaired tank back into position with a hoist
  
• Install mounting bolts with correct torque, ensuring rubber pads are not crushed
  
• Reconnect fuel supply and return lines according to labels
  
• Reattach the vent line and any breather hoses
  
• Plug in the fuel level sender harness and secure it away from moving parts
  
• Install all protective plates and guards, ensuring no lines are pinched
  

• Fill the tank with clean, filtered diesel
  
• Use the hand priming pump or electric priming feature (if equipped) to push fuel through filters
  
• Follow the manufacturer’s procedure for “Fuel System – Prime” to remove air
  
• Start the engine and let it run at low idle, checking carefully for leaks at all connections
  
• Monitor fuel filter restriction indicators and watch for any sudden power loss
  

• Better packaging around the rear frame to protect tanks in harsh environments
  
• Improved accessibility through side and rear doors for routine maintenance
  
• Integration with emissions strategies that demand very clean fuel supply
  

• Contamination trends
  • Machines working around makeshift fuel storage or old farm tanks show much higher rates of water and sludge in their fuel systems.
    
  • Regular draining of water and sediment from the tank and filters is often cheaper than one injector replacement.
    
• Time estimates
  • In a well-equipped shop, a tank removal, internal cleaning, and reinstallation can often be done within a working day if no welding is needed.
    
  • In the field with limited lifting gear, the same task might stretch into two days, especially if guards and rear attachments complicate access.
    
• Documentation
  • Mechanics frequently stress the value of taking photos and labeling lines when multiple hoses and harnesses surround the tank.
    
  • A simple mistake like swapping return and supply lines can cause hard-to-diagnose performance issues.
    

• Drain water and sediment from the tank at the intervals recommended for your duty type, or more often if you suspect poor fuel quality
  
• Keep detailed notes of filter changes and any recurring contamination issues
  
• Inspect breather and vent lines so the tank can “breathe” without pulling in dirt or moisture
  
• If you notice recurring power loss, unusual filter plugging, or visible rust in drained fuel, plan for a tank inspection instead of endlessly changing filters
  
• When the tank must be removed, use proper lifting gear and follow methodical disassembly and reassembly steps
  

The Rise of Digital Freight Platforms in Construction
In recent years, the construction logistics sector has seen a surge in digital platforms aiming to streamline dump truck scheduling, dispatch, and payment. Among these, Trux—also known as TruxNow—has positioned itself as a specialized solution for dump truck operators and contractors. The platform functions similarly to rideshare apps, connecting drivers with hauling jobs in real time, offering route optimization, digital ticketing, and automated invoicing.
Founded in Massachusetts, Trux was developed to address inefficiencies in the bulk material hauling industry. The company claims to have facilitated millions of loads and partnered with hundreds of contractors across the U.S. Its core value proposition lies in reducing idle time, improving transparency, and accelerating payment cycles for independent truckers.
Features and Functionality of Trux
Trux offers a mobile app and web dashboard with the following capabilities:

• Job matching based on location, truck type, and availability
  
• Real-time GPS tracking and route management
  
• Digital load ticketing and time stamping
  
• Automated invoicing and payment processing
  
• Driver performance analytics and fleet utilization reports
  

• Market saturation: In regions with limited construction activity, job postings may be sparse.
  
• Rate variability: Prices fluctuate based on demand, and drivers may find themselves accepting lower-paying jobs to stay active.
  
• Platform fees: Trux charges a service fee, which can reduce net earnings.
  
• Dependence on app stability: Technical glitches or GPS errors can affect job tracking and payment accuracy.
  

• DumpTruckLoads: A marketplace for bulk hauling jobs
  
• HaulHub: Focused on material delivery and construction logistics
  
• LoadUp: Offers on-demand hauling for debris and aggregates
  

Introduction
Buying an older Komatsu forklift without an identification plate can feel like adopting a stray machine with no paperwork and no history. You know it lifts, you know it runs, but you do not know what it is. Model, serial number, year, and engine information all matter for parts, manuals, and safe operation. When the data plate is missing, owners are forced to become detectives, using casting numbers, frame stampings, paint schemes, and engine details to reconstruct the machine’s identity.
This article walks through a real-world style scenario of identifying an older Komatsu forklift using only physical clues on the machine, with added explanations, terminology notes, and practical advice drawn from forklift industry experience.
Komatsu Forklift Background
Komatsu is one of the major global manufacturers of construction and material-handling equipment. The company’s roots can be traced back to 1921 in Komatsu City, Japan, and by the 1960s–1970s it had become a significant player in forklifts, competing with Toyota, Nissan, and others worldwide.
Komatsu internal-combustion forklifts are typically designated with codes like:

• FG – Forklift, Gas (LPG/gasoline)
  
• FD – Forklift, Diesel
  
• 15 / 18 / 20 – Nominal lifting capacity in decitonnes (e.g. 15 ≈ 1.5 t, 20 ≈ 2.0 t)
  

• Manufacturer
  
• Model designation
  
• Serial number
  
• Capacity at specific lift heights and load centers
  
• Mast type and attachments
  

• Parts sourcing – Dealers and aftermarket suppliers usually ask for model and serial number first.
  
• Load rating and safety – Without the official rating, the operator may overestimate capacity.
  
• Regulatory and inspection compliance – Many safety standards require a clearly legible data plate.
  

• Check visual clues
  • Overall size and mast height
    
  • Tire type (pneumatic or cushion)
    
  • Paint scheme and approximate era
    
  • Fuel type (LPG bottle, gasoline tank, diesel, or dual-fuel)
    
• Look for stamped numbers on the frame
  • Komatsu commonly stamped numbers into the frame or fender, not just on riveted plates.
    
  • Typical locations include:
    • Top flange of the frame between the counterweight and the front of the hood
      
    • Left or right front fender
      
    • Areas near the tilt cylinder mounts
      
• Inspect the engine
  • Identify engine family: casting marks, displacement, and type label.
    
  • In many small Komatsu forklifts, Toyota industrial engines such as the 4P series were used.
    

• Numbers near hydraulic components can sometimes be component numbers or sub-assembly IDs, not the truck serial number.
  
• Genuine truck serials are typically stamped on non-removable structural parts, like the main frame or integral fenders.
  

• Sit in the operator’s seat.
  
• Dismount to the right side of the truck.
  
• Turn to face the truck, raise the hood.
  
• Scan the top flat/rolled portion of the frame, between the counterweight region and where the hood closes.
  
• Also check the left or right front fender, especially just ahead of the firewall, where the sheet metal often forms part of the frame.
  

• Code:

  M016D-110772
  
  

• The prefix (e.g.
  
  Code:

  M016D
  ) often encodes:
  • Series or chassis type
    
  • Fuel and capacity class
    
  • Market or design variations
    
• The numeric portion (e.g.
  
  Code:

  110772
  ) is generally the sequential serial number for that model.
  

• Code:

  FG15-123456
  → Forklift Gas 1.5 t, serial 123456
  

• An LPG/gas-type layout
  
• A Toyota 4P 1493 cc engine
  
• Physical size similar to a 1.5 t–1.8 t unit
  
• A frame stamping of
  
  Code:

  M016D-110772
  
  

• The machine is likely in the FG15 class (around 1.5-ton capacity).
  
• Code:

  110772
  serves as the unique serial number.
  
• Code:

  M016D
  identifies a specific Komatsu design series or manufacturing batch.
  

• Marked 4P
  
• Displacement 1493 cc
  

• Industrial engine – A variant of an automotive engine optimized for constant-speed, heavy-duty work, often derated for longevity and fitted with different manifolds, governor, and cooling systems.
  

• 4-cylinder, inline, overhead-valve (OHV) design
  
• Roughly 1.5 L displacement
  
• Output often around 35–45 kW (47–60 hp) in industrial tune
  
• Designed for long life at moderate RPM
  

• Oil selection guidance
  
• Tune-up parts (plugs, cap, rotor, filters)
  
• Many repair procedures
  

• Paint schemes
  • Earlier Komatsu IC forklifts were often all yellow.
    
  • Later series introduced blue and white striping and more modern graphics.
    
• Letter-based year codes
  • Some Komatsu serial systems use letters to represent model years.
    
  • In one widely shared reference, a mapping appears for later machines (largely 2010s), such as:
    • K = 2012
      
    • L = 2013
      
    • M = 2014
      
    • N = 2015
      
    • P = 2016
      
    • Q = 2016 (overlap depending on series)
      
    • R = 2017
      
    • S = 2018
      
    • T = 2019
      

• All-yellow paint
  
• Styling and controls
  
• Engine family (Toyota 4P)
  

• Spare parts ordering
  • Hydraulics, mast rollers, steering components, and transmission parts can vary between similar-looking models.
    
  • With the wrong model, you can end up with expensive mismatched parts.
    
• Service manuals
  • Correct workshop manuals and parts books depend on series and serial number ranges.
    
  • Procedures such as torque specs, hydraulic pressures, and wiring diagrams differ between models.
    
• Safety and capacity
  • Replacing or modifying masts, forks, or attachments without referencing the original capacity plate can lead to overloads.
    
  • Re-plating the truck with a correct or replacement capacity plate may require model and serial confirmation.
    

• Locate hard-stamped numbers
  • Inspect:
    • Left/right front fenders, especially ahead of the firewall
      
    • Top of the frame under/near the hood
      
    • Areas around the counterweight junction
      
  • Use:
    • Wire brush or flap wheel
      
    • Sandpaper to remove paint and rust carefully
      
  • Record any alphanumeric codes such as
    
    Code:

    M016D-110772
    .
    
• Photograph the machine
  • Take clear photos from multiple angles:
    • Side view (showing counterweight and frame lines)
      
    • Front view (showing mast type)
      
    • Rear view
      
    • Close-ups of any numbers and engine markings
      
• Identify the engine
  • Look for:
    • Cast-in codes (e.g.
      
      Code:

      4P
      )
      
    • Displacement markings (e.g.
      
      Code:

      1493cc
      )
      
    • Any remaining tags or stickers
      
  • Use the engine type to narrow down likely forklift models that used that powerplant.
    
• Estimate capacity
  • Measure:
    • Fork thickness, width, and carriage size
      
    • Overall size of the truck
      
  • Compare visually with known 1.5-ton vs. 2-ton forklifts.
    
  • Most small Komatsu LPG trucks with Toyota 4P engines are in the 1.5–2.0 t range.
    
• Consult dealer or specialist
  • Provide:
    • Stamped number (e.g.
      
      Code:

      M016D-110772
      )
      
    • Photos and engine details
      
  • Komatsu dealers or experienced forklift shops can often match these to an exact model and series.
    

• Engine oil
  • For industrial Toyota 4P engines, a common recommendation is:
    • Multigrade oil such as 10W-30 or 15W-40
      
    • API classification suitable for gasoline engines (SJ or later), sometimes mixed-fleet oil for LPG units
      
  • Change intervals often around 250 hours, but older machines benefit from more frequent changes if usage is severe.
    
• Hydraulic oil
  • Many small forklifts run an ISO VG 32–46 hydraulic oil or equivalent.
    
  • Reservoir and filters should be cleaned and replaced on a regular schedule.
    
• Cooling system
  • The 4P engine should be run with the proper coolant mixture (usually around 50% ethylene glycol, 50% water) and maintained to avoid overheating.
    
• Fuel system
  • For LPG units:
    • Inspect vaporizer/regulator, filters, and hoses regularly.
      
  • For gasoline:
    • Keep carburetor and fuel lines clean and protected against stale fuel.
      

• Frame-stamped codes like
  
  Code:

  M016D-110772
  are key clues.
  
• Engine information such as a Toyota 4P 1493 cc motor helps narrow down model and capacity.
  
• Paint color, styling, and expert memory can place the machine in the right era.
  

Understanding the Brake System in Older Hydraulic Equipment
Many older cranes and construction machines, such as the Grove RT-58C rough terrain crane, use a hydraulic drum brake system. These systems rely on a master cylinder to generate hydraulic pressure, which is transmitted through brake lines to wheel cylinders that actuate brake shoes against a drum. Over time, air can enter the system during maintenance or component replacement, leading to a spongy pedal or complete loss of braking force unless the pedal is pumped repeatedly.
In the case of a full brake system overhaul—including new linings, wheel cylinders, lines, and a master cylinder—air entrapment is almost inevitable. Even with fluid present at the bleeder valves, residual air pockets can cause the pedal to feel soft or require pumping to build pressure.
Why the Pedal Goes Soft After Sitting
A common symptom is a firm pedal immediately after bleeding, which then goes soft after a few minutes of rest. This typically indicates that the brake shoes are not adjusted close enough to the drum surface. When the shoes are too far from the drum, the wheel cylinder pistons must travel farther to make contact, consuming more fluid volume and reducing pressure at the pedal.
This issue is compounded if the master cylinder has a small bore or if the system lacks residual pressure valves. These valves are designed to maintain slight pressure in the lines to keep the wheel cylinder cups expanded and reduce air ingress.
Proper Bleeding Procedure for Hydraulic Drum Brakes
To ensure a firm pedal, follow this sequence:

• Begin with the wheel farthest from the master cylinder (usually right rear)
  
• Use a clear hose submerged in brake fluid to monitor air bubbles
  
• Have an assistant pump the pedal slowly and hold it down
  
• Open the bleeder valve, allow fluid and air to escape, then close the valve before releasing the pedal
  
• Repeat until no air bubbles are visible
  
• Move to the next wheel and repeat the process
  

• Turn the adjuster until the shoes lightly drag against the drum
  
• Back off slightly to prevent overheating during operation
  
• Repeat for all wheels
  

• Use DOT-rated brake fluid compatible with your system
  
• Replace rubber hoses if they show signs of swelling or cracking
  
• Periodically check for leaks at wheel cylinders and master cylinder
  
• Store equipment in dry conditions to prevent moisture contamination
  

Overview of the Bobcat S175 and Its Role on Jobsites
The Bobcat S175 is a mid-size skid steer loader that became popular in the mid-2000s for its balance of compact dimensions, lifting capacity and versatility. With an operating capacity around 1,750 lb and a typical operating weight in the 2.8–3.0 ton range, it is widely used in construction, landscaping, small demolition and farm work. Auction and dealer records show that thousands of S175 units from model years 2005–2012 have circulated through the global used-equipment market, making it one of the more common skid steer models in its class
Because these machines are often used in tough conditions and constantly started, stopped and moved between attachments, their electrical systems—especially starter and safety circuits—are frequent sources of trouble. A 2007 S175 is old enough that wiring, switches and connectors may have seen 15+ years of vibration, moisture and owner modifications. That is the backdrop for a typical real-world story: somebody has been “under the dash,” wires have been pulled from the starter switch, and now the machine will not behave as it should.
This article walks through the logic of diagnosing and correctly reconnecting the starter switch wiring on an S175-era skid steer, explains the key components and safety circuits, and then expands into practical advice to avoid similar electrical headaches.
Key Electrical Components Around the Starter Circuit
Before dealing with pulled-off wires, it helps to understand the main elements involved in starting and running a skid steer like the S175:

• Battery
  Provides power to the entire electrical system. On older machines, loose posts, corroded lugs or undersized replacement batteries are common issues.
  
• Ignition / starter switch
  A multi-position switch (typically OFF, RUN, START, sometimes ACCESSORY) that distributes power to different circuits depending on key position. Internal contacts connect different terminals at each position.
  
• Starter solenoid
  A heavy-duty relay mounted on or near the starter motor. When energized, it engages the starter gear and applies battery power to the starter motor.
  
• Safety interlock system
  On an S175, interlocks typically ensure that:
  • The operator is in the seat
    
  • Seat bar is down
    
  • Parking brake / traction lock is in the correct state
    
  • Controls are enabled
    Only when certain conditions are met will the machine allow crank or traction.
    
• Fuses and relays
  These protect and control high-current circuits like the starter, traction lock solenoid, glow plugs and auxiliaries. A single blown fuse can mimic a wiring failure.
  

• B or BATT
  Main battery feed into the switch. Always hot (12 V) when the battery is connected.
  
• ACC
  Accessory circuit, powered in ACC and RUN positions.
  
• IGN or RUN
  Supplies power to the machine’s control electronics and instrumentation when key is in RUN and START.
  
• S or START
  Sends power to the starter relay/solenoid only when the key is turned to START.
  
• G or ground (on some switches)
  Not always present, but some switches have a dedicated ground for indicator circuits.
  

• Identify the battery feed wire
  • Turn the battery disconnect ON.
    
  • With the key removed and all switches OFF, probe each loose wire with a multimeter referenced to chassis ground.
    
  • The wire that shows a steady 12–13 V is almost certainly the battery feed that must go to the B terminal.
    
• Identify ground or neutral wires
  • If there is a black or dark-colored wire that shows continuity to the machine frame (0 Ω or close to it), that is likely ground.
    
  • Some key switches do not use a ground terminal; others use it for indicator lamps or buzzer circuits.
    
• Identify the start-signal wire
  • Ask a helper to hold the key in the START position while you probe the other loose wires with a test lamp or meter connected to battery positive as reference.
    
  • The wire that only shows step-down potential (or completes the circuit through the meter/test lamp) during START is usually the starter relay control wire.
    
• Sort out RUN / ACC circuits
  • Turn the key to RUN and mark which wires now become live (or complete the circuit).
    
  • If multiple harness wires show 12 V only in RUN or ACC, note that some may feed gauges, ECU, fuel solenoid, and auxiliary circuits.
    

• Seat bar must be down
  
• Seat switch must confirm an operator is present
  
• Parking brake status must be correct
  
• Traction lock must be released in a controlled way
  

• Indicator lights or code display on the panel
  
• Beeper patterns when you power up
  
• That all interlock sensors are plugged in and not damaged
  

• The accessory feed ended up on the START terminal.
  
• The starter relay wire was on the ACC terminal.
  
• The battery feed and RUN feed were reversed.
  

• In RUN, the instrument panel flickered weakly because it was fed through the wrong internal contact path.
  
• In START, the accessory would jump to life, but the starter solenoid never got power.
  
• After several attempts, a 30-amp fuse blew, killing the entire circuit.
  

• Visual inspection
  • Look for rubbed-through insulation, melted connectors, and obviously loose or broken wires.
    
  • Check that the key switch is firmly mounted and not rotating in the panel, which can stress connections.
    
• Battery and main connections
  • Measure battery voltage at the posts (should be about 12.6 V at rest for a healthy battery).
    
  • Wiggle and clean the main lugs, including ground connection to chassis.
    
• Fuses and relays
  • Do not just “look” at fuses; check them with a meter or test light.
    
  • Swap a suspect relay with a known good one of the same type and verify that the relay socket isn’t burnt or loose.
    
• Key switch operation
  • With a multimeter, confirm which terminals connect in each key position.
    
  • Verify that the battery feed is reaching the switch and that the START terminal actually energizes when you turn the key.
    
• Starter relay and solenoid
  • Verify that the relay coil gets power and ground when the key is turned.
    
  • Check continuity and voltage drop through the main contacts when energized.
    
  • Listen for a solid “click” from the starter solenoid; no sound could mean no signal or a failed solenoid.
    
• Safety circuit verification
  • Confirm seat, seat bar and other interlock switches are plugged in and operating.
    
  • If your machine has a code display, retrieve any active codes before cycling power.
    

• Label every wire before removal
  Use small numbered tags or even masking tape and a marker. A few minutes now saves hours later.
  
• Photograph everything
  Take clear photos of the back of the switch, fuse panel and harness routing before you touch anything.
  
• Use proper terminals and tools
  Avoid twisted-together wires and household connectors. Use crimp-on terminals, heat-shrink, and correct gauge wire.
  
• Protect from moisture and vibration
  Seal splices, tie up harnesses securely and keep wires off sharp edges. Vibration is relentless on a skid steer.
  
• Keep an updated wiring diagram in the machine
  Even a generic schematic for your model year can be a lifesaver when problems appear on a jobsite.
  

• Expect electrical wear
  Sixteen to twenty years of use means connectors, switches and wires are no longer in their prime.
  
• Treat the key switch and starter wiring as critical infrastructure
  Do not let untrained hands “guess” at connections.
  
• Remember that simple things fail often
  Blown fuses, loose grounds and corroded lugs remain more common than failed controllers.
  
• Consider preventive electrical refresh
  Proactively replacing an aging ignition switch, cleaning fuse/relay panels and inspecting harnesses can avoid job-stopping failures.