Hydraulic motor connections

           It is very important that the hydraulic motor is connected appropriately, allowing it to operate faultlessly. We point out to the importance of making sure that the hoses that we are about to plug to the hydraulic motor are clean. Also, it is very important to ensure that the oil in the machine has not been contaminated, e.g. by former fault in the hydraulic system. If you are sure that that the hoses and the entire hydraulic system are free from contamination, you may proceed to identifying the hydraulic hoses connected to the hydraulic motor of the the final drive.

The easiest for identification are the hoses feeding the hydraulic motor, since they are the thickest (and generally the largest). These allow the final drive to move left and right. Then, identify the so-called return, meaning: the overflow hose. If there are only three hoses for connecting, then the smallest of them will be the overflow hose. If there are four hoses, then identification of that hose may be a little problematic, but there is luckily an easy and effective way to do this: simply place the two other similar hoses in a container, such as a bucket (after connecting the main hoses to the hydraulic motor, naturally), and then run the machine in second gear. The hose from which oil will start leaking is the second gear! After this short experiment you may connect the overflow and the second gear to the hydraulic motor correctly. There are also cases where the drive brake is connected separately. This hydraulic hose is usually the smallest and leaks oil after the final drives moves.

When buying a new complete final drive from KETRAL, you will find properly coloured plugs facilitating identification of hydraulic connections. These are always marked with the same code:

- black colour means feeding hoses (marked P1 and P2),

- red colour means overflow (return, marked T1 and T2)

- green colour means second gear.

Remember also that all our final drives are delivered with quick assembly manual. We kindly suggest that you read it before performing assembly, in order to avoid mistakes. We particularly remind you that the location of individual connections may be different than with the factory-fitted part!


Few remarks on return (overflow).

All types of hydraulic motors have their internal lubrication points, allowing to lubricate the system to prevent its seizure. However, the lubrication oil must return to the system somehow, and this is ensured by the overflow hose, which returns the oil back to the sump. In the case the return of this oil is prevented (due to blocking, e.g. by a plug, or due to wrong connection), pressure in the hydraulic motors increases, usually causing severe damage in the whole hydraulic motor. Proper connection of the overflow hose is a precondition for correct operation of a hydraulic motor. When connecting a hydraulic motor, it is also very important to ensure that it is properly vented by filling it with hydraulic oil in order to prevent dry operation of the hydraulic parts.


42-350 Koziegłowy, woj. śląskie
Rzeniszów, ul. Zielona 2