Introduction
The master switch, also known as the battery disconnect switch, is a critical component in skid steer loaders. Its primary function is to isolate the battery from the electrical system, ensuring safety during maintenance and preventing unauthorized use. Understanding its importance, proper installation, and common troubleshooting steps can enhance the longevity and reliability of your equipment.
Function and Importance
The master switch serves several key purposes:

• Safety: By disconnecting the battery, it prevents accidental starts and electrical shorts during maintenance.
  
• Security: Acts as a deterrent against theft, as the machine cannot be started without re-engaging the switch.
  
• Battery Preservation: Disconnecting the battery helps in preserving its charge and extending its lifespan.
  

• Location: Typically, the switch is installed near the battery compartment for easy access.
  
• Type of Switch: Choose between a rotary or knife-style switch based on your preference and space constraints.
  
• Cable Connection: It's generally recommended to install the switch on the negative (ground) cable. This practice reduces the risk of accidental shorts.
  
• Quality: Opt for a switch with solid brass electrical connections and a durable housing to withstand harsh conditions.
  

• No Power: If the machine shows no signs of power, ensure the master switch is in the "on" position and that all connections are clean and tight.
  
• Intermittent Power: Corrosion or loose connections at the battery terminals or the switch itself can cause intermittent power loss. Regular inspection and cleaning are essential.
  
• Electrical Shorts: Installing the switch on the positive cable can increase the risk of shorts. Always install on the negative side to mitigate this risk.
  

• Seat Safety Switches: These ensure the operator is seated before the machine can be started.
  
• Parking Brake Interlocks: Prevent the machine from starting unless the parking brake is engaged.
  
• Emergency Stop Buttons: Allow for immediate shutdown in case of an emergency.
  

The 490 Series and Its Mechanical Heritage
The John Deere 490 excavator, produced in the late 1980s and early 1990s, represents a transitional era in construction equipment—bridging mechanical simplicity with early electronic integration. Built under a partnership with Hitachi, the 490 shares design DNA with the EX series, including hydraulic architecture and structural layout. With an operating weight around 10 metric tons and a dig depth exceeding 18 feet, the 490 was widely used in utility trenching, site prep, and small-scale demolition.
Unlike later models with full electronic control systems, the original 490 relied heavily on direct hydraulic actuation. However, some units were equipped with a microprocessor module for monitoring gauges and auxiliary functions, leading to confusion when wiring was modified or removed.
Terminology and Component Notes
- Swivel Joint (Center Joint): A rotary manifold that transfers hydraulic fluid between upper and lower frames, enabling travel motor function while the cab rotates.
- Travel Motors: Hydraulic motors mounted on each track drive, responsible for forward and reverse movement.
- Return Filter: A hydraulic filter that cleans fluid returning to the reservoir, protecting pumps and valves.
- Case Drain Flow: Low-pressure fluid returning from motor housings, used to monitor internal leakage.
- Microprocessor Module: An early electronic unit used for gauge control and auxiliary monitoring, not engine or hydraulic management.
Symptoms of Travel Failure and Initial Observations
One operator reported that after 30 minutes of operation, the machine would barely move in either direction, though all other hydraulic functions remained normal. The return filter had been replaced, and the hydraulic tank drained and cleaned. No metal or brass debris was found, suggesting no catastrophic internal failure.
Key symptoms included:

• Gradual loss of travel power after warm-up
  
• Both tracks affected equally
  
• No visible hydraulic leaks
  
• Electrical system modified from 24V to 12V
  
• Microprocessor disconnected and wiring altered
  

• Visually inspect the swivel joint for missing bolts, corrosion, or fluid seepage
  
• Confirm that all mounting bolts are present; missing bolts can cause misalignment and seal distortion
  
• Disassemble the joint carefully, noting the presence of bearing balls and high-pressure seals
  
• Replace all O-rings and seals with OEM-grade components rated for hydraulic pressure
  
• Inspect bearing surfaces for grooving; resurface on a lathe if necessary
  

• Most original components—lights, relays, sensors—were designed for 24V operation
  
• Running them on 12V may cause underperformance or failure
  
• Rewiring the machine with manual gauges and a master switch is viable but requires careful planning
  
• Use a programmable tachometer or photo tach gun to measure engine RPM during hydraulic testing
  
• Ensure alternator output matches battery configuration and system load
  

• Install pressure gauges at the pump outlet and motor inlet ports
  
• Compare readings to factory specs (typically 4,000–5,000 psi under load)
  
• Measure case drain flow to detect internal motor leakage
  
• Swap travel motor hoses to isolate directional faults
  
• Monitor temperature rise in the swivel joint and motors during operation
  

• Using hydraulic seal suppliers to match samples
  
• Consulting cylinder rebuild shops for compatible materials
  
• Ordering from regional distributors with legacy inventory
  
• Avoiding overseas sourcing unless part numbers are confirmed
  

Introduction
The Caterpillar D7F, introduced in 1969, is a medium-sized track-type tractor renowned for its robust performance and versatility. Part of Caterpillar's D7 series, the D7F was designed to handle a variety of tasks, including heavy-duty earthmoving, land clearing, and construction projects. Its combination of power, durability, and adaptability has made it a valuable asset in various industries.
Engine and Powertrain
The D7F is powered by the Caterpillar 3306 diesel engine, a six-cylinder, turbocharged unit known for its reliability and efficiency. This engine delivers approximately 180 horsepower, providing ample power for demanding tasks. The machine features a three-speed powershift transmission, allowing for smooth gear transitions and enhanced control over different terrains.
Dimensions and Weight
The D7F's dimensions vary depending on the specific configuration and attachments. However, typical specifications include:

• Length: Approximately 17 feet 4 inches
  
• Width: Around 11 feet 4 inches
  
• Height: Varies based on blade and cab configurations
  
• Operating Weight: Between 31,300 to 41,100 pounds
  

• Hydraulic Capacity: 24 gallons (90.8 liters)
  
• Hydraulic Pressure: 2,450 psi (168.9 bar)
  
• Pump Flow: 60 gallons per minute (227.1 liters per minute)
  

1. Transmission Compatibility: Early models of the D7F experienced transmission issues due to the use of the D7E's transmission, which was designed for a lower-speed, high-torque engine. The higher-revving 3306 engine in the D7F required a different transmission setup. Later models addressed this by incorporating a version of the D6C transmission, which was more suitable for the engine's characteristics.
   
2. Starting Problems: Some D7F operators have encountered starting issues, often related to the fuel system. A small button on the front of the fuel pump, located above the manual pump, must be pushed forward to enable starting. If this button sticks or fails to trip forward, it can prevent the engine from starting. Regular cleaning and lubrication of the pump area can help prevent this problem.
   
3. Power Loss and Overheating: Instances of power loss combined with overheating and dropping oil pressure have been reported. These symptoms may indicate fuel delivery or lubrication issues. Thorough inspection of the fuel system and oil circulation is recommended to diagnose and address the root cause.
   

The Volvo L70 and Its Cooling System Design
The Volvo L70 wheel loader is a mid-sized machine designed for aggregate handling, construction, and municipal work. First introduced in the 1980s and refined through several generations, the L70 series is known for its balance of power, maneuverability, and operator comfort. With an operating weight around 13,000 to 14,000 kg and a bucket capacity of 2.3 to 2.5 cubic meters, it’s a staple in European and North American fleets.
The engine cooling system in the L70 is critical to maintaining performance and longevity. At the heart of this system is the engine fan, which draws air through the radiator and intercooler to regulate engine temperature. A damaged or missing fan can lead to overheating, reduced efficiency, and long-term engine damage.
Terminology and Component Notes
- Engine Fan: A rotating blade assembly driven mechanically or hydraulically, used to pull cooling air through the radiator.
- Radiator Core: The heat exchanger that dissipates engine coolant heat into ambient air.
- Fan Shroud: A molded cover that directs airflow and improves cooling efficiency.
- Viscous Coupling: A fluid-based clutch that engages the fan based on temperature, reducing parasitic drag.
- Intercooler: A secondary heat exchanger used to cool compressed air from the turbocharger before it enters the engine.
Symptoms of Fan Failure and Field Diagnosis
Operators may notice a strange noise from the engine bay, often mistaken for a misfire or belt squeal. In reality, the absence or damage of the fan blades can cause airflow imbalance, leading to poor cooling and erratic engine behavior. If the fan is missing entirely, the loader may overheat within minutes of heavy operation, especially during summer or high-load conditions.
Common symptoms include:

• Rising coolant temperature under load
  
• Reduced engine power due to heat-related derating
  
• Audible whine or vibration from the fan hub
  
• Lack of airflow through the radiator fins
  
• Warning lights or shutdown codes triggered by high temperature
  

• Contact salvage yards specializing in construction equipment. Many maintain inventories of Volvo components, including fans and shrouds.
  
• Reach out to aftermarket suppliers who produce compatible fan assemblies for Volvo loaders. Ensure the blade pitch, diameter, and hub pattern match the original.
  
• Consider contacting tractor parts distributors, as some agricultural fans may share dimensions with Volvo units.
  
• Verify the fan’s compatibility with the engine model (often a Volvo TD or D-series diesel) and the cooling system layout.
  

• Inspect the fan hub and viscous coupling for wear or leakage. Replace if necessary.
  
• Ensure the fan blades are balanced and free of cracks or distortion.
  
• Torque mounting bolts to manufacturer specifications to prevent vibration.
  
• Check the fan shroud for alignment and clearance. A misaligned shroud can reduce airflow and cause blade contact.
  
• Flush the radiator and intercooler to remove debris and scale before restarting the machine.
  

The New Holland LS170 Skid Steer Loader, part of the Super Boom™ series, has been a staple in the compact equipment market since its introduction in the early 2000s. Renowned for its vertical lift design, this machine offers impressive reach and lifting capabilities, making it a preferred choice for various applications, including construction, landscaping, and agriculture.
Engine and Performance Specifications
At the heart of the LS170 is the New Holland N844T turbocharged diesel engine, delivering 52 horsepower. This engine provides a balance between power and fuel efficiency, ensuring the loader can handle demanding tasks without excessive fuel consumption. The machine's hydrostatic transmission allows for smooth and responsive control, essential for precise maneuvering in tight spaces.
Dimensions and Operational Capacity

• Length with Bucket: 10.44 ft (3.18 m)
  
• Width Over Tires: 5.48 ft (1.67 m)
  
• Height to Top of Cab: 6.24 ft (1.90 m)
  
• Wheelbase: 3.55 ft (1.08 m)
  
• Ground Clearance: 7.88 in (20 cm)
  
• Operating Weight: 5,540 lbs (2,513 kg)
  
• Rated Operating Capacity: Approximately 1,765 lbs (800 kg)
  

1. Hydraulic System Faults: Some users have experienced sudden bogging down and loss of movement, often indicative of transmission charge pressure faults. It's advisable to inspect the hydraulic charge pump, pressure sensors, and fluid levels regularly to prevent such issues.
   
2. Turbocharger Failures: A notable concern involves turbocharger malfunctions leading to engine oil consumption. Operators should monitor turbo performance and address any irregularities promptly to avoid severe engine damage.
   
3. Wheel Bearing Wear: Over time, wheel bearings may exhibit signs of wear. Regular inspection and timely replacement can prevent further damage to axle shafts or housings.
   
4. Steering and Drive Chain Issues: Instances of unresponsive steering or "free-wheeling" have been reported, often linked to drive chain adjustments. Ensuring proper tension and alignment can mitigate these problems.
   
5. Loader Pivot Point Stress: In intensive applications, such as manure handling, the loader's pivot point may experience stress, leading to potential failures. Reinforcing this area can enhance durability.
   

• Regular Fluid Checks: Monitor hydraulic, engine oil, and coolant levels. Replace filters as per the manufacturer's recommendations.
  
• Grease Daily: Lubricate all pivot points and moving parts daily to reduce wear and prevent rust.
  
• Inspect Tires: Check tire pressure and tread regularly to maintain stability and traction.
  
• Monitor Engine Performance: Listen for unusual sounds and watch for warning lights. Address any anomalies immediately.
  
• Keep the Machine Clean: Regular cleaning prevents debris buildup, which can lead to overheating and mechanical issues.
  

A Truck with Alaskan Heritage and Custom Engineering
The Kenworth C500 acquired by a seasoned logger in Washington State is no ordinary spare truck—it’s a piece of custom-built history. Originally one of three units brought down from Alaska, this particular C500 was engineered by Bill Paulson of McPaul Cat and Crane, a name well known in the Pacific Northwest for building extreme-duty rigs. While Paulson’s iconic yellow truck is widely recognized, this unit was originally built for Mike Plaas and later changed hands.
The truck features a 25,000-pound steer axle paired with a 25,000-pound Bendix Skagit drop axle, making it a formidable platform for heavy hauling. It has since been upgraded with 46,000-pound Rockwell drive axles sourced from Mack trucks, equipped with a 6.14 gear ratio and double lockers—ideal for traction in steep, muddy terrain. With a 224-inch wheelbase and a Big Cam 400 Cummins engine, the truck was designed to pull hard and survive abuse.
Terminology and Component Notes
- Drop Axle: An auxiliary axle that can be lowered to distribute load, often used in logging and heavy haul applications.
- Double Lockers: Differential locks on both axles, allowing full traction across all drive wheels.
- Brownie Box: A secondary transmission, often a 3- or 4-speed auxiliary gearbox used to multiply gear options.
- Big Cam 400: A 14-liter Cummins diesel engine known for its mechanical simplicity and torque output, popular in 1980s heavy trucks.
- 20918B Transmission: An 18-speed Eaton Fuller gearbox, offering a wide range of ratios for both highway and off-road use.
Transmission Failure and Upgrade Strategy
On its first trip under new ownership, the original 9-speed transmission failed—a common risk when pushing older drivetrains under load. Rather than repair the outdated gearbox, the owner sourced a 20918B 18-speed to pair with the existing 4-speed Brownie. This combination offers unmatched flexibility, especially in logging operations where terrain varies from steep grades to soft ground.
The auxiliary transmission, identified as a 1241 twin countershaft unit, is being retained. This setup allows gear splitting and torque multiplication, giving the operator control over speed and power delivery in challenging conditions. The decision to keep the Brownie reflects a philosophy shared by many veteran loggers: more gears mean more control, and more control means fewer broken parts.
Sourcing and Supply Chain Challenges
With new Kenworth trucks delayed due to factory backlogs and Cummins engine shortages, the decision to rebuild and upgrade an older unit is both practical and strategic. The owner noted that his new truck order may not arrive until the following year, prompting him to consider importing another C500 from Canada or fully restoring the current rig.
This reflects a broader trend in the industry. Supply chain disruptions have led many operators to invest in used equipment, especially models with proven mechanical reliability. In some cases, older trucks are being retrofitted with modern components, blending legacy durability with updated performance.
Operational History and Restoration Context
The truck spent most of its working life near Morton, Washington, before relocating to Redmond for several years. It was known in logging circles and had a reputation for toughness. A photo from its earlier days shows it stationed at the Kapowsin camp, still bearing the marks of hard use.
Now back on the road, the truck is being prepared for active duty. The owner’s new shop and yard are operational, though he notes the need for a skilled mechanic—a sentiment echoed across the industry as experienced technicians retire and replacements grow scarce.
Customization and Future Plans
Suggestions from fellow operators include adding stainless steel or chromium air intake stacks to give the truck a more aggressive look. With its rugged build and distinctive profile, the truck is already earning nicknames like “King of the C500s” and “Redd Fox of the C500s,” a nod to its character and lineage.
Plans for further upgrades may include:

• Replacing worn suspension bushings and torque rods
  
• Installing LED lighting and modern gauges
  
• Rebuilding the cab interior for comfort and noise reduction
  
• Adding hydraulic assist steering for better maneuverability
  
• Upgrading the cooling system for sustained heavy load operation
  

Bobcat Company, established in 1947 and headquartered in West Fargo, North Dakota, is renowned for its innovative skid-steer loaders and compact equipment. One of the key features that has contributed to the versatility and popularity of Bobcat machines is their attachment systems, particularly the bucket interchangeability. This flexibility allows operators to switch between various buckets and attachments, enhancing the machine's utility across different tasks.
Understanding the Bobcat Quick Attach System
The Bobcat Quick Attach system, introduced in the 1970s, revolutionized the way operators interacted with their machines. This system enables quick and secure attachment changes without the need for tools, significantly reducing downtime and increasing productivity. The standard configuration includes a mounting plate with two locking pins that secure the attachment to the skid steer. Operators can engage or disengage attachments by operating a lever from inside the cab or manually from outside the machine. This design has been widely adopted by most skid steer manufacturers, making it easier for operators to use attachments from different brands on their Bobcat machines.
Factors Affecting Bucket Compatibility
While the Quick Attach system provides a universal interface, several factors can influence the compatibility of buckets and other attachments:

1. Mounting Plate Configuration: Most modern Bobcat skid steers utilize the Standard Skid Steer Quick Attach (SSQA) system. However, some older models or specialized machines might use different mounting systems. For example, Bobcat's mini skid steers have historically used proprietary attachment plates, such as the Bobcat MT plate, which may not be compatible with the SSQA system.
   
2. Attachment Size and Weight: Attachments vary in size and weight, and it's crucial to ensure that the bucket's size is appropriate for the skid steer's specifications. Using an attachment that exceeds the skid steer's weight capacity can lead to instability and potential damage.
   
3. Hydraulic Flow and Pressure: Many attachments, such as augers and trenchers, require hydraulic power to operate. Bobcat skid steers come with standard-flow hydraulic systems, typically providing 15-25 GPM, while some models offer high-flow systems delivering 26-40 GPM or more. It's essential to match the attachment's hydraulic requirements with the skid steer's capabilities to ensure optimal performance.
   

The 310SJ and Its Transmission Architecture
The John Deere 310SJ is part of the 310 series of backhoe loaders, a lineage that has defined mid-sized utility machines for decades. Produced in the mid-2000s, the SJ variant introduced refinements in cab ergonomics, emissions compliance, and electronic transmission control. It features a powershift transmission with electronically actuated solenoids that govern gear selection, allowing seamless transition between forward and reverse without clutching.
The transmission system relies on a combination of mechanical components—planetary gear sets, clutch packs—and electronic controls, including solenoids, relays, and sensors. When forward drive fails while reverse remains functional, the issue typically lies in the control logic or hydraulic actuation of the forward clutch pack.
Terminology and Component Notes
- Powershift Transmission: A gearbox that allows gear changes under load using hydraulic clutches and electronic solenoids.
- Forward Solenoid: An electrically actuated valve that directs hydraulic pressure to engage the forward clutch pack.
- Clutch Pack: A set of friction discs and plates that transmit torque when pressurized.
- Transmission Control Module (TCM): An electronic unit that interprets operator input and manages solenoid activation.
- Neutral Drop: A condition where the transmission disengages unexpectedly, often due to electrical faults or pressure loss.
Symptoms and Initial Observations
In one case, a 310SJ began intermittently dropping into neutral while in forward gear. Eventually, it failed to engage forward altogether, though reverse remained operational. The operator confirmed that the forward solenoid passed a basic electrical test and that fuses and relays were intact. This points to a deeper issue—either hydraulic or electronic—that affects only the forward clutch engagement.
Typical symptoms include:

• No movement when forward gear is selected
  
• Reverse gear functions normally
  
• No error codes displayed on the dash
  
• Forward solenoid clicks but does not engage clutch
  
• Machine previously exhibited intermittent forward disengagement
  

• Use a pressure gauge to test hydraulic pressure at the forward clutch port. Compare readings to factory specs (typically 200–300 psi under load).
  
• Swap the forward and reverse solenoids to see if the issue follows the component. If reverse fails after the swap, the solenoid is likely faulty.
  
• Inspect wiring harness for chafing, corrosion, or loose connectors—especially near the transmission case and under the cab.
  
• Check the TCM for stored fault codes using a compatible diagnostic tool. Some faults may not trigger dash alerts but still affect operation.
  
• Verify that the transmission fluid is clean, at proper level, and free of air bubbles. Contaminated or aerated fluid can prevent clutch engagement.
  

• Worn clutch discs in the forward pack can prevent torque transfer even when pressure is applied.
  
• A damaged piston or seal inside the clutch housing may leak pressure, preventing engagement.
  
• Debris or varnish buildup in the valve body can restrict fluid flow to the forward circuit.
  

• Change transmission fluid and filters every 1,000 hours or annually, whichever comes first.
  
• Use OEM-approved hydraulic fluid with anti-wear additives and correct viscosity.
  
• Inspect solenoid connectors and wiring during routine service.
  
• Avoid abrupt gear changes under load, which can stress clutch packs and solenoids.
  
• Keep diagnostic logs and note any intermittent behavior before it becomes chronic.
  

The Case 1840 Skid Steer Loader, manufactured from 1988 to 2001, is a versatile and durable machine widely used in construction, landscaping, and agriculture. Despite its robust design, operators may encounter various issues over time. Understanding these common problems and their solutions can help maintain the machine's performance and longevity.
Engine and Starting Problems
One of the most frequently reported issues with the Case 1840 is starting problems. Operators have reported instances where the engine starts but then dies unexpectedly. This can be due to a faulty ignition switch, starter relay, or issues with the fuel system. For example, a user reported that the engine fires and runs for a short time, then shuts off immediately with no sputtering, and will not restart until after a random wait period.
Hydraulic System Issues
Another common problem is slow or unresponsive hydraulics. This can be caused by low hydraulic fluid levels, contaminated fluid, or issues with the hydraulic pump. For instance, a user reported that the right side of the machine was slow to respond, and upon disassembling the pump, found that the valve plate and cylinder block face were worn, leading to pressure loss.
Electrical System Faults
Electrical issues can also affect the Case 1840. Operators have reported problems such as the engine sputtering and dying when turning on flood lights, which could indicate a short circuit or grounding issue.  Additionally, some users have experienced complete power loss with no lights or buzzer when turning the key to the "on" position, suggesting potential issues with the ignition switch or wiring.
Parking Brake Problems
The parking brake system in the Case 1840 can sometimes be problematic. Users have reported that the parking brake pin may not disconnect properly when there is tension on it from the gear, leading to a stubborn parking brake that is difficult to release.
Maintenance and Troubleshooting Tips
To address these issues, regular maintenance and timely troubleshooting are essential:

• Starting Problems: Check the ignition switch, starter relay, and fuel system components for wear or damage. Ensure that the battery is fully charged and connections are clean and tight.
  
• Hydraulic Issues: Regularly check hydraulic fluid levels and quality. Replace filters as needed and inspect the hydraulic pump and valves for wear or damage.
  
• Electrical Faults: Inspect wiring and connections for signs of wear or corrosion. Test fuses and relays, and ensure that all safety interlock switches are functioning correctly.
  
• Parking Brake: Regularly inspect the parking brake system for proper operation. Lubricate components as needed to ensure smooth engagement and release.
  

The 966D and Its Cab Design Evolution
The Caterpillar 966D wheel loader, introduced in the late 1970s and produced through the early 1980s, was part of CAT’s push toward more powerful, operator-friendly mid-sized loaders. With an operating weight of approximately 45,000 pounds and a bucket capacity ranging from 4.5 to 5.5 cubic yards, the 966D was widely used in quarrying, aggregate handling, and construction site loading. Its cab design, while rugged, was relatively spartan compared to modern loaders, and many components—including the windshield washer system—were tucked away in unconventional locations.
Unlike newer models with clearly labeled service panels and modular washer reservoirs, the 966D’s washer bottle was often hidden beneath the operator’s seat or embedded within the cab’s lower structure. This design choice reflected the era’s emphasis on mechanical durability over service accessibility.
Terminology and Component Notes
- Washer Bottle: A plastic or metal reservoir that holds windshield washer fluid, connected to a pump and spray nozzles.
- Suspension Seat Plate: The mounting base for the operator’s seat, often concealing components like the washer bottle or motors.
- Rubber Plug: A removable seal used to access hidden compartments or service points.
- Cab Vent Panel: A sheet metal cover housing heater vents or auxiliary components, sometimes mistaken for washer system access.
Finding the Washer Bottle in the 966D
Operators unfamiliar with the 966D’s layout often struggle to locate the washer bottle. It is not in the engine compartment, nor is it visible from standard cab inspection points. Instead, the bottle is typically mounted beneath the operator’s seat, behind a rubber plug embedded in the seat’s suspension plate.
To locate and access the washer bottle:

• Slide the seat fully backward while seated
  
• Look down toward the front of the seat base
  
• Identify a rubber plug or small access panel in the mounting plate
  
• Remove the plug to reveal the washer bottle and pump assembly
  
• Inspect for wiring and fluid lines to confirm functionality
  

• Inspect for cracks or leaks and replace with a compatible aftermarket reservoir
  
• Test the pump motor using a 12V source to confirm operation
  
• Flush the fluid lines with warm water and compressed air to remove sediment
  
• Replace clogged nozzles with universal spray tips
  
• Use a washer fluid rated for freezing temperatures if operating in cold climates