Final drive, travel motor, track drive: what is what?
Zoltan Gal, Managing Director FinalDriveUpdated
On an excavator, final drive, track drive and travel motor usually mean the same unit: a hydraulic motor with a flanged planetary gearbox that turns the sprocket. Strictly speaking, travel motor only means the hydraulic part and travel gearbox only the gearbox. In German the unit is called Fahrantrieb.
Anyone looking for a replacement drive comes across many names for the same part. Dealers, manufacturers and workshops use them differently. This overview helps you read quotes correctly and order the right part.
The terms at a glance
| Term | Meaning |
|---|---|
| Final drive | Complete unit of hydraulic motor and planetary gearbox. The most common term. |
| Travel motor | Strictly speaking only the hydraulic motor. Often used for the whole unit. |
| Travel gearbox, planetary gearbox | The mechanical part that converts the motor's fast rotation into slow, powerful rotation. |
| Track motor, track drive | Drive of a tracked machine, on an excavator the same as final drive. |
| Sprocket | The toothed wheel that engages the track. It is bolted to the final drive. |
| Fahrantrieb, rijmotor, moteur de translation | German, Dutch and French terms for the final drive. |
How a final drive is built
- Hydraulic motor: In most excavators an axial piston motor. Pressurised oil moves pistons that turn a shaft.
- Valve block: Contains brake and counterbalance valves, on machines with two speeds also the shift valve for second speed.
- Parking brake: A multi-disc brake holds the machine when there is no travel command.
- Planetary gearbox: Usually two stages that strongly reduce speed and increase torque.
- Housing and hub: The hub turns with the sprocket, sealed by a floating seal.
How it works
- The machine's hydraulic pump supplies high-pressure oil via the rotary joint to the travel motor.
- The oil drives the hydraulic motor. The direction depends on which of the two supply lines the oil flows into.
- The planetary gearbox converts the rotation into slow, powerful movement.
- The sprocket on the hub moves the track.
- Oil that leaks past the pistons in the motor returns to the tank unpressurised via the case drain line.
Why the lines matter
Depending on the machine, a final drive has 2, 3, 4 or 5 hydraulic ports: two supply lines, a case drain line, often a pilot line for second speed and on some machines a brake line. How to assign them is explained in removing and installing a final drive.
Buying the right part
Quotes for a "travel motor" do not always mean the complete unit. Ask whether the gearbox is included. We always supply our final drives complete with travel motor and planetary gearbox. Find the right drive in the catalogue by brand or via the part number on the type plate.
Frequently asked questions
Is a travel motor the same as a final drive?
In everyday use, yes. Strictly speaking the travel motor is only the hydraulic motor, the final drive is the complete unit with planetary gearbox.
What is a final drive on an excavator?
The unit of hydraulic motor and planetary gearbox that turns the sprocket and moves the track.
What is a final drive called in German?
Fahrantrieb, also Fahrmotor, Endantrieb or Kettenantrieb. They all mean the same unit.
Is the sprocket part of the final drive?
No, the sprocket is bolted to the hub and is a separate part. For some models we supply it, this is stated on the model page.