Indigo Books – Page 72

Replacing the gearbox on a Liebherr PR712B, PR712BM, PR712BL, PR722B, PR722BM, or PR722BL Litronic Dozer is a substantial task that requires attention to detail, an understanding of heavy machinery, and a methodical approach to ensure a successful outcome. Find additional details in the downloadable manual……

Let’s delve into the step-by-step process, ensuring we cover all necessary tools and procedures involved.

### Tools Required

1. **Socket Set**: A complete set including metric sizes, typically 10mm to 24mm, with a ratchet and extensions for tight spaces.

2. **Wrenches**: Both open-end and box wrenches, especially in the sizes mentioned above.

3. **Torque Wrench**: For correctly tightening bolts to manufacturer specifications, which is critical for the integrity of the assembly.

4. **Pry Bar**: This tool will assist in removing components that may be stuck due to age or corrosion.

5. **Floor Jack and Jack Stands**: For securely lifting the dozer and supporting it safely while you work underneath.

6. **Creeper**: A mechanic’s creeper will make it easier to slide under the dozer without straining your back.

7. **Pneumatic or Electric Impact Wrench**: To speed up the process of removing heavy bolts, particularly in the gearbox assembly.

8. **Shop Vacuum**: To clean out any debris or dirt that may have accumulated in the gearbox area.

9. **Clean Rags and Shop Towels**: For keeping components clean during disassembly and reassembly.

10. **Gearbox Oil**: The appropriate lubricant for the gearbox, as specified in the Liebherr service manual.

11. **Sealant or Gasket Maker**: Depending on the design, you may need a specific sealant to ensure there are no leaks.

12. **Hoist or Engine Crane**: For lifting the heavy gearbox out and back into place, as these components can be quite hefty.

### Preparation

Before starting any work on the dozer, it’s crucial to ensure you have a clean, safe workspace. Park the dozer on a level surface, and engage the parking brake. It’s always a good practice to disconnect the battery to prevent any electrical issues during the process.

1. **Safety Gear**: Equip yourself with safety glasses, gloves, and steel-toed boots. A hard hat is advisable, especially if working in an area where other machinery is operating.

2. **Documentation**: Refer to the Liebherr service manual specific to the model you’re working on. This manual will provide crucial torque specifications, part numbers, and detailed diagrams.

### Step-by-Step Process

#### 1. **Lifting the Dozer**

– Use the floor jack to lift the front of the dozer.
– Place jack stands securely under the frame to support the weight.
– Ensure the dozer is stable before crawling underneath.

#### 2. **Draining the Gearbox Oil**

– Locate the oil drain plug on the gearbox. This is typically a hex bolt.
– Using a socket and ratchet, remove the drain plug and allow the old oil to drain into a suitable container for disposal.
– After draining, replace the drain plug securely.

#### 3. **Removing Components for Access**

– **Remove the Driveshaft**: Depending on the configuration, this may require removing a few bolts using the impact wrench.
– **Disconnect Electrical Connectors**: Carefully unplug any electrical connectors that lead to the gearbox. take pictures or label them if necessary to ensure correct reattachment.
– **Remove the Gearbox Cover**: If there’s a cover over the gearbox, remove it by unscrewing the bolts with a socket. Keep track of all bolts and components.

#### 4. **Unbolting the Gearbox**

– **Locate the Mounting Bolts**: There will typically be several large bolts securing the gearbox to the frame. Using the impact wrench or a ratchet, remove these bolts.
– **Support the Gearbox**: Before removing the last bolt, ensure that the gearbox is adequately supported with a hoist or engine crane to prevent it from falling.

#### 5. **Removing the Gearbox**

– Once all Still attached to the gearbox, which could impede removal.

#### 6. **Inspecting the New Gearbox**

– Before installation, inspect the new gearbox for any shipping damage and verify that it matches the specifications of the old one.
– Ensure all mounting surfaces are clean and free of debris.

#### 7. **Installing the New Gearbox**

– Carefully position the new gearbox into place, aligning it with the mounting points.
– Use the hoist to hold it steady while you insert the mounting bolts. Begin with a few bolts to secure it before tightening.

#### 8. **Tightening bolts and Components**

– Use a torque wrench to tighten all bolts to the specifications provided in the service manual. This step is critical to prevent future issues.
– Reconnect any electrical connectors and hoses that were disconnected during disassembly.

#### 9. **Reinstalling the Driveshaft**

– If you removed the driveshaft, reposition it and secure it with bolts, using the impact wrench to tighten.

#### 10. **Reinstalling Gearbox Cover**

– If there was a cover, reinstall it and ensure all bolts are tightened properly.

#### 11. **Refilling Gearbox Oil**

– Remove the fill plug and use a funnel to refill the gearbox with the appropriate oil until it reaches the recommended level. Replace the fill plug securely.

#### 12. **Final Checks**

– Double-check that all tools are removed from the area, and all components are secured.
– Reconnect the battery and perform a final inspection.

#### 13. **Testing**

– Start the dozer and let it idle for a few minutes. Observe for any unusual noises or leaks.
– Test drive the dozer in a safe area to ensure the gearbox is functioning correctly.

### Conclusion

Replacing the gearbox on a Liebherr PR712B, PR712BM, PR712BL, PR722B, PR722BM, or PR722BL Litronic Dozer is a task that requires careful planning, the right tools, and a thorough understanding of the machine’s workings. Always remember to follow safety protocols and refer to the manufacturer’s documentation for specific guidelines. With patience and precision, you can successfully replace the gearbox and ensure the longevity of your dozer.
A Constant velocity (CV) joint is a critical component in a vehicle’s drivetrain, primarily found in front-wheel drive and all-wheel drive systems. Its main function is to transmit power from the engine through the transmission to the wheels while allowing for the up-and-down motion of the suspension and the side-to-side movement required during steering. The CV joint is designed to maintain a constant rotational speed without any significant increase in friction, which is essential for smooth vehicle operation.

There are two common types of CV joints: the ball-type and the tripod-type. The ball-type CV joint, often found on the outer end of the axle, uses spherical balls that fit into grooves, allowing for a greater range of motion. This design enables it to handle sharp turns and varying angles required in front-wheel drive vehicles. The tripod-type joint, typically located on the inner side, utilizes three sliding trunnions that allow for linear motion and is often used in applications where less angular movement is needed.

CV joints are typically encased in rubber or plastic boots filled with grease to protect them from dirt, moisture, and debris. Regular maintenance is crucial, as a damaged CV boot can lead to grease leakage and eventual joint failure, resulting in costly repairs and unsafe driving conditions. Overall, CV joints are essential for the efficient and reliable operation of modern vehicles, contributing to both performance and safety on the road.