DRESSTA TD-25M EXTRA, Service Manual

Page: 343 / 595

HYDRAULICS
SECTION 10
Page 1
DRESSTA TD-25M EXTRA
SERVICE /SPECIAL TOOLS
1. SERVICE /SPECIAL TOOLS
DESCRIPTION TOOL NUMBER
Digital Optical Tachometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337 7462
Test Pressure Gauges Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 910-50-0005
GENERAL
2. DESCRIPTION
The hydraulic system generally consists of the equipment hydraulic system and fan drive hydraulic
system, which are interconnected to share a common hydraulic reservoir for efficient operation.
Equipment Hydraulic System (Fig.’s 10.1 and 10.2)
The equipment hydraulic system of the machine includes control, blade and ripper equipment
circuits and it will depend upon the application and the attachments ordered. Fig.10.1 and Fig. 10.2
illustrate what is available and are to be used to trace the hydraulic oil flow. Following is a brief
description of the hydraulic components.
Hydraulic Reservoir
The reservoir is bolted to the right fender next to the fuel tank. It is a one piece welded assembly
with a 100 mesh magnetic suction strainer, and an external 170 [kPa] pressure 2 [kPa] vacuum
relief breather. This vacuum relief valve will protect the pumps from cavitation as well as
maintaining pressure in the reservoir. Refer to the OPERATOR’S MANUAL for service of this
valve.
The reservoir acts as a storage tank for the dozer equipped hydraulic system oil. The remainder of
oil fills the lines and system components.
Hydraulic Equipment Pump
The positive displacement three element pumping cartridges are of the rotary vane type with shaft
side loads hydraulically balanced. The pump is flange mounted to the torque converter and is
driven by the converter accessory drive gear. The flow rate depends on the pump speed at which it
is driven. For a further description of pump operation, refer to PUMPS in SECTION 10A.
Control System
The control valves used in this system are mounted on the right fender. This system utilizes either
a one or three spool valve depending on whether or not a ripper is used and tilt control valve
which will or tilt/pitch control valve which depend on optional equipment. The valves are controlled
by pilot pressure and actuated by the pilot control valves mounted in the operator’s compartment.
Hydraulic Cylinders
The blade and ripper cylinders are the single stage double acting type. Hydraulic pressure is
introduced through ports at either end to actuate the piston.