Complete workshop service manual with electrical wiring diagrams for Komatsu GD825A-2. It's the same service manual used by dealers that guaranteed to be fully functional and intact without any missing page.

This service & repair manual (including maintenance, overhaul, disassembling & assembling, adjustment, tune-up, operation, inspecting, diagnostic & troubleshooting…) is divided into different sections. Each section covers a specific component or system with detailed illustrations. A table of contents is placed at the beginning of each section. Pages are easily found by category, and each page is expandable for great detail. The printer-ready PDF documents work like a charm on all kinds of devices.

"Shop Manual (SEBM002308).pdf"
Komatsu GD825A-2 Shop Manual; 926 pages
MACHINE MODEL SERIAL No.
GD825A-2 11001 and up

EXCERPT:
PILOT REDUCING VALVE
Function
• The pilot reducing valve acts to control the pressure needed to actuate the transmission spools.
Operation
• The oil from the pump passes through the pilot filter and enters port A of pilot reducing valve (1).
The oil passes through port B and enters through the orifice of transmission spool (2) to fill the inside of port C.
• When the pressure inside port C rises, pressurized oil flows from orifice "a" of pilot reducing valve (1) and goes to port D.
As a result pilot reducing valve (1) moves to the right, and ports A and Bare shut off, so the pressurized oil at port C is maintained at the same pressure.

Function of pilot circuit drain
This pilot valve functions as a reducing valve primary pressure: 1.47 MPa (15 kg/cm2); secondary pressure: 1.06 MPa (1 0.8 kg/cm2). If the reducing valve does not have drain port a at the secondary side, it is impossible to obtain the specified reducing pressure.
For example, at the Neutral position, if there is no secondary pressure at drain port a, theoretically the pressure generated at the secondary side is the same pressure as the primary pressure. (Actually, it is not as high as the primary side because of leakage from the valve spool.)