Removal and Replacement of a Final Drive from the machine
Below are some basic tips to help you to fit a new final drive and connect the hydraulic hoses / pipes correctly. Don’t forget the original machine manufacturers procedures should be followed where possible.
Removing the old drive
- Remove the track and loosen the sprocket bolts.
- Tip: It is much easier to loosen the sprocket bolts before removing the final drive.
- Remove the track motor cover plate from inside the undercarriage frame.
- Sling the final drive and take the weight.
Caution: Final drives are very heavy
- Mark the hydraulic hoses so you can later identify them.
- Remove the hoses and cap them, plug the ports on the track motor. It is very important to seal all hydraulic hoses and ports to prevent contamination of the hydraulic system.
- From inside the track frame remove the bolts securing the final drive to the frame.
- Swing out the final drive.
Tip. If the final drive is tight in the track frame do not hit the travel motor in an attempt to free it. It will damage the motor. Lever the final drive out from outside of the track frame.
Fitting a new drive
Fitting a new final drive is the reverse of removal but pay special attention when connecting the pipes as incorrect fitting can cause an immediate failure of the travel motor.
Refer to the Bolt Torque Settings page of this web site when tightening bolts
How many? There may be 2, 3, 4 or sometimes 5 hydraulic connections to a travel motor and gearbox.
What are they for?
- Two hydraulic lines are required to power the motor. These are the “Flow and Return” lines.
- A case drain / Leak-off. Very important to connect this correctly — See below.
- A two speed line to control the travel motor speed.
- A brake line. If fitted it is usually connected to the gearbox rather than the travel motor.
ATTENTION Case drain — Leak-off. All piston type hydraulic motors leak oil from the barrel and piston assembly (sometimes called the rotating group assembly) into the motor casing. This leakage is deliberate and lubricates the piston slippers and swash plate (or thrust plate) as well as the interface between the valve plate (or lens plate) and the cylinder block. The oil that leaks into the motor casing has to find it’s way back to the tank under very little pressure and a leak-off pipe (or drain line) runs from the travel motor to the hydraulic tank for that purpose. If the leak-off pipe is not connected or becomes blocked or pressurised, oil pressure will build up in the motor casing and can, and usually does, cause catastrophic damage to the travel motor and often the final drive gearbox. It is therefore vital to ensure that the leak-off pipe is connected correctly, is not obstructed and has no significant back pressure.