Transporting a Cat 120G Without Hydraulic Power

[MikePhua]

The Caterpillar 120G motor grader is one of the most iconic road‑building machines ever produced. Known for its reliability, mechanical simplicity, and long production life, the 120G became a global standard for municipal road maintenance and small‑to‑mid‑size contractors. Many units built in the 1980s and 1990s are still working today, especially in developing regions where mechanical durability is valued over electronics.
Transporting a 120G with a failed engine presents a unique challenge because the moldboard, circle, and lift cylinders normally rely on hydraulic power to position the blade for loading. When the engine is blown, operators must rely on mechanical methods to lift and rotate the blade safely.
Development Background of the 120G
Caterpillar introduced the G‑series graders to replace the earlier 12F and 120F models. The 120G quickly became the best‑selling grader in its class due to:

• A robust mechanical transmission
  
• A simple open‑center hydraulic system
  
• A reliable 3304 diesel engine
  
• Excellent visibility and operator ergonomics
  
• A durable circle drive with worm‑gear rotation
  

The 120G sold in large numbers across North America, Latin America, Africa, and Asia. Its reputation for longevity made it a favorite among government fleets and contractors working in remote areas.
Terminology notes:

• Circle: The large rotating ring that allows the moldboard to pivot.
  
• Moldboard: The grader blade used for cutting, shaping, and leveling.
  
• Lift cylinders: Hydraulic cylinders that raise and lower the moldboard.
  
• Worm gear: A self‑locking gear mechanism used to rotate the circle.
  
• Lowboy: A trailer designed for hauling heavy equipment.
  

Challenges of Transporting a Dead 120G
When the engine cannot run, the grader loses hydraulic pressure. This prevents:

• Lifting the moldboard
  
• Rotating the circle
  
• Positioning the blade for transport
  

To load the machine onto a lowboy, the blade must be raised and secured, and the circle must be rotated to prevent interference with the trailer deck.
The primary concerns include:

• Avoiding excessive hydraulic oil loss
  
• Preventing damage to hoses and cylinders
  
• Ensuring the blade is safely secured for transport
  
• Working without steering or brake assist
  

Methods for Raising the Moldboard Without Hydraulics
Operators have several practical options for lifting the moldboard when hydraulic power is unavailable.
Loosening Hydraulic Lines
One method is to crack open the hydraulic lines on the lift cylinders. This allows oil to escape as the cylinders are manually lifted using another machine such as an excavator, loader, or crane.
Advantages:

• Simple and fast
  
• Requires minimal disassembly
  

Disadvantages:

• Hydraulic oil spills must be contained
  
• Requires another machine to lift the blade
  

Experienced operators recommend using pans or containers to catch the oil, minimizing environmental impact.
Removing the Lift Cylinders
Another option is to unbolt and remove the lift cylinders entirely. Once removed, the moldboard can be lifted with a chain hoist, come‑along, or another machine.
Advantages:

• No oil spill
  
• Full mechanical control of the moldboard
  

Disadvantages:

• More labor‑intensive
  
• Requires careful reinstallation later
  

This method is often preferred when working in environmentally sensitive areas or when oil containment is difficult.
Using Float Position
Some graders have a float function on the lift controls. If float is available, placing the controls in float may allow the moldboard to be lifted manually without hydraulic resistance.
However, this depends on:

• Whether the machine has float
  
• Whether any lock valves require hydraulic pressure to release
  

If float does not work, mechanical methods must be used.
Rotating the Circle Without Engine Power
The 120G uses a worm‑gear circle drive, which is self‑locking. This means the circle will not rotate freely without mechanical assistance.
Options for rotating the circle include:

• Connecting external hydraulic power to the circle turn hoses
  
• Manually turning the worm gear by engaging the splines
  
• Opening the top of the circle gearbox and rotating the gear directly
  

These methods require mechanical skill and may involve removing covers or applying external force.
Additional Considerations
Because the engine is blown, the grader will also lack:

• Power steering
  
• Air pressure for the parking brake
  
• Hydraulic assist for articulation
  

Operators must plan for:

• Limited maneuverability
  
• The need for towing or pushing
  
• Ensuring the parking brake is released using external air if required
  

Field Experiences and Practical Advice
Operators who have transported dead graders often emphasize the importance of patience and preparation. One mechanic recalled lifting a 120G blade using a chain hoist suspended from a tree limb when no other equipment was available. Another described using a portable hydraulic power pack to rotate the circle on a remote jobsite.
These stories highlight the adaptability required when working with older machines in challenging conditions.
Caterpillar Company Background
Caterpillar has been a leader in motor grader design since the early 20th century. The 120 series, in particular, became one of the most successful grader lines ever produced. The 120G’s long production run and global popularity helped solidify Caterpillar’s dominance in the road‑building sector.
The company’s focus on durability, parts availability, and operator comfort contributed to strong worldwide sales and a loyal customer base.
Practical Recommendations

• Use another machine to lift the moldboard safely.
  
• Contain hydraulic oil if cracking lines is necessary.
  
• Consider removing lift cylinders to avoid spills.
  
• Use external hydraulic power or mechanical rotation for the circle.
  
• Ensure the blade is chained securely before transport.
  
• Verify that the parking brake is released before towing.
  
• Plan for limited steering and maneuverability.
  

Conclusion
Transporting a Caterpillar 120G with a failed engine requires creativity, mechanical knowledge, and careful planning. By using mechanical lifting methods, external hydraulic assistance, or controlled disassembly, operators can safely position the moldboard and rotate the circle for loading. Despite the challenges, the 120G remains a durable and respected machine whose design allows for field repairs and improvisation even decades after its introduction.