5-2 Lower Mechanism: Travel Drive Unit 3. Piping configuration 1) Main pipe Set up the main pipe of the motor in the horizontal position or in the upright position. (See Figure 28). If the pipe is set up below the horizontal position and left stopped for a long period of time, the hydraulic oil may leaks from and air may accumulate in the motor circuit, causing aeration or cavitation resulting in a malfunction such as runaway phenomena on starting the motor. 2) Drain pipe The piston motor case must always be filled with hydraulic oil. Therefore, If there are two oil drain ports, use the upper one for drain piping (See Figure 28). If there is only one oil drain port, use it for piping. Important
Be sure to perform drain piping. Failing to do so may cause the following problems due to rising pressure in the motor case: 1. Parking brake cannot be released due to the pressure in the motor case. In this case, brake dragging will occur, causing fatal damage to the parking brake functions. 2. The pressure rise in the motor case will cause damage to the oil seals and fatal damage to the piston motor section.
Perform drain piping using either T1 or T2.
Perform drain piping using the upper port (T1 or T2). Top
Bottom
Bottom
Figure 28. Piping to the motor
142
