Identifying the hydraulic pipes / hoses.
- The flow and return pipes are usually the two biggest. They can be rubber hoses or steel pipes and are a matching pair.
- Case drain. If there are only three pipes the smaller of the three will almost certainly be the case drain. If there are four or more pipes the case drain is likely to be bigger than all but the flow and return. It is a low pressure pipe and is sometimes attached to the travel motor with a ferrule and jubilee clip. Whilst disconnected oil will continually flow at low pressure from the pipe while the engine is running.—IT IS VERY IMPORTANT TO LOCATE AND CONNECT THIS PIPE CORRECTLY.
- Two speed. This tends to be the smallest pipe of all. Oil will not flow from this pipe unless the machine is in high speed mode.
- Brake port. If fitted this pipe will be small and will pressurise only when the travel lever is operated.
- 3 Ton mini excavator final drive with integrated 2 speed travel motor showing 4 front entry ports
- 6 Ton midi excavator final drive with integrated 2 speed travel motor showing 4 entry ports. Note the somewhat unusual position of the case drain port.
- 12 Ton excavator final drive with “plug in” 2 speed travel motor and separate brake port in the gearbox.
- 13 Ton excavator final drive with integrated 2 speed travel motor showing 4 front entry ports.
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.
Travel Motor Port Identification
| Single Speed Final Drives | ||
| A – B PORTS: (Flow and Return) These are the main inlet/outlet ports and are usually the largest ports on the travel motor. Where there are four or more ports they will always be located in the centre of the flange. | 1.5 Ton mini excavator final drive with single speed orbital type travel motor showing 2 entry ports. Note there is no need for a case drain port on this motor. | 8 Ton mini excavator final drive with integrated single speed travel motor showing 4 front entry ports. The case drain ports are interconnected and either can be used. |
| C1 – C2 Ports: (Case Drain) Most modern final drives will have two case drain ports, one on either side of the A/B ports. The position of the drain port can be changed by placing a plug in either C1 or C2. It’s important to always attach the case drain hose to the uppermost port and leave the bottom port plugged. Some drives have a single case drain port between the A/B ports. It’s critical that the case drain hose is correctly identified; attaching a pressurized hose to this port can cause both hydraulic and mechanical failure. | Two Speed Final Drives | |
| 3 Ton mini excavator final drive with integrated two speed travel motor showing 5 front entry ports. The case drain ports are interconnected and either can be used. | 13 Ton excavator final drive with integrated two speed travel motor showing 5 front entry ports. The case drain ports are interconnected and either can be used. | |
| D Port: (two Speed) The two speed port tends to be the smallest on the travel motor and can be found in different positions depending on the model and manufacturer. It can be found on the front of the flange centred between the A/B ports or located on the side or rear of the flange. | ||
| 3.5 Ton mini excavator final drive with integrated two speed travel motor showing 4 front entry ports and with the two speed port to the side. The case drain ports are interconnected and either can be used | ||
| Brake Port: With the exception of tracked dumpers and other faster moving tracked machines it is unusual to find a brake port in an integrated gearbox and travel motor as the brake is usually controlled automatically. Where a separate “plug-in” motor is used the brake port is usually found on the gearbox.If equipped the port location will be clearly shown in the included installation instructions. | ||
| 36 Ton excavator final drive with “plug in” two speed travel motor. Note that there is another case drain port out of view opposite the port shown, either can be used. | ||
| 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. | ||
| 12 Ton excavator final drive with integrated two speed travel motor. The case drain port is centred between the A/B ports and the two speed port is at the rear. | ||
| 20 Ton excavator final drive with integrated two speed travel motor. The case drain ports are located either side of the A/B ports and the two speed port is at the rear. | ||
