Expansion and Exchange
Removing and replacing a chain drive from the machine
Below you will find some basic tips to help you install a new travel drive and connect the hydraulic hoses / lines correctly. Remember that the original machine manufacturer’s installation instructions should be followed wherever possible.
Removal of the old chain drive
Dismantling the travel drive, i.e. the entire travel drive with the hydraulic motor, is not particularly difficult. Nevertheless, we would like to give you a few tips at this point that may be helpful.
To dismantle the travel drive, you should first remove the rubber track or open the crawler track. Then loosen the screws on the side of the drive wheel before removing the final drive. Remove the cover plate of the drive motor from the inside of the chassis frame. It is now recommended to mark the hydraulic lines so that they can be easily identified later.
You can now dismantle the hydraulic lines. It is very important to protect all hydraulic hoses and connections from dirt so as not to damage the new travel drive later. Remove the screws securing the travel drive to the frame from the inside of the machine frame and lever out the travel drive from the inside. Caution, the travel drives are heavy parts, the safety instructions must be strictly observed
Installation of a new chain drive
Installing a new traction drive is the reverse procedure, but pay particular attention when connecting the pipes, as incorrect installation can cause the traction motor to fail immediately.
Before assembling the entire travel drive, it is advisable to lubricate the chambers of the travel motor and the hydraulic lines excessively with hydraulic oil to ensure appropriate lubrication and to remove the air from the travel drive.
You can then start assembling the travel drive. The chain drive must first be attached to the excavator frame. When mounting the drive on the frame, make sure that the contact surfaces between the frame and the travel motor are clean and that the bolts are tightened with the appropriate force. The torques with which the chain drive must be tightened can be found in the manufacturer’s original operating instructions.
After the drive motor has been attached to the machine frame, the hydraulic lines must now be connected. Please note that the arrangement of individual connections may vary from manufacturer to manufacturer. To make your work easier, the connections of our travel drives are marked in color:
- Connection input / output - green marking
- Leakage/drain connection - blue marking
- 2nd speed connection - red marking
At this point, we would like to point out once again that an incorrect or incomplete connection of the traction drive can, in the worst case, lead to the complete failure of the traction motor.
Identification of the connecting cables.
The travel drives can have 2, 3, 4 or even 5 hydraulic lines. There are different operating pressures in the lines, which is why they must always be connected correctly.
The supply lines: these lines have the largest diameter, which is why they are the easiest to identify. These lines supply the drive motor with over 200 bar and provide the necessary power to move the excavator or mini-excavator forwards and backwards. An incorrect connection is relatively difficult (due to the nominal connection diameter). In the worst case, the machine will move in the wrong direction.
Return line, leakage line, expansion lines: – as the name suggests, these lines are used to return the oil that leaks into the engine housing to the tank under very low pressure. If the leakage line is not connected, or is blocked or pressurized, oil pressure builds up in the engine case and can and usually will cause catastrophic damage to the traction motor. It is therefore essential to ensure that the leakage line is connected correctly, is not blocked and has no significant back pressure. It is generally recommended to use the upper connection so that any air bubbles can be released.
2nd speed connection – the newer and larger construction machines are equipped with 4 hydraulic lines to ensure faster movement. These lines are very similar to the leakage lines, identification is somewhat more problematic. However, there is a simple and safe method to ensure the two lines are connected:
- Place the two similar hoses in a bucket (after the geared motor has been installed and the IN/OUT hoses have been connected),
- Start the excavator at the lowest speed,
- Move the gearshift to the 2nd speed,
- The hose from which the oil emerges is connected to the 2nd speed point. The connection for the second speed of the travel drive can be located either at the front, side or rear and is marked in red on our travel drives.
Connection of a travel drive with two speeds to mini excavators with one speed: For mini excavators with three lines and one speed, the connection for the second speed is not used, but must not be closed, but must be connected with a T-piece to the drainage hose or directly to the other drainage connection so that no pressure builds up in the valve – see pictures
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