525B Wheel Skidder and 535B Wheel Skidder Hydraulic and Steering System Caterpillar

General Information

Usage:

525B 3KZ

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Illustration 1	g00711074
Schematic of the Implement Hydraulic System (1) Brake control group (2) Left steering cylinder (3) Decking blade cylinders (4) Arch cylinders (5) Boom cylinders (6) Tong cylinders (7) Rotator (8) Relief valve for the rotator motor (9) Right steering cylinder (10) Priority flow control valve (11) Steering valve (12) Decking blade valve (13) Pressure reducing valve (14) Arch control valve (15) Relief valve for the priority flow control valve (16) Differential lock control valve (17) Accumulator (Pilot oil and Differential lock) (18) Boom control valve (19) Tong control valve (20) Rotator control valve (21) Secondary steering pressure switch (secondary steering arrangement) (22) Primary steering pressure switch (secondary steering arrangement) (23) Front differential lock and rear differential lock (24) Pilot valve (25) Secondary steering pump and motor (if equipped) (26) Hydraulic pump assembly (27) Hydraulic tank and filter elements

Reference: For the hydraulic schematic of the 525B Wheel Skidder and 535B Wheel Skidder, refer to Schematic, "525B Wheel Skidder and 535B Wheel Skidder Hydraulic System" for the machine that is being serviced.

The hydraulic system provides oil for the braking system, the steering system, the decking blade, the differential lock, the boom, the arch, the tong, and the rotator.

The hydraulic system contains the following components. Hydraulic tank and filter elements (27), hydraulic pump assembly (26), secondary steering pump and motor (25) (if equipped), priority flow control valve (10), brake control group (1), steering valve (11), pilot valve (24), differential lock control valve (16), accumulator (17), decking blade valve (12), pressure reducing valve (13), arch control valve (14), boom control valve (18), tong control valve (19), rotator control valve (20), rotator (7), relief valve (8) and cylinders (2), (3), (4), (5), (6), and (9). The hydraulic tank and filter elements (27) is common to all of the systems.

Reference: For more information about the secondary steering arrangement, refer to the Service Manual module Systems Operation, "Secondary Steering System" for the machine that is being serviced.

Several attachments that are available have components that are not shown on the schematic Illustration 1. The component includes a six bank valve with the implement valves, a swing boom control valve and a hydraulic retrieval device (HRD) valve.

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Illustration 2	g00711080
Left Side of Machine (2) Left steering cylinder (3) Decking blade cylinders (4) Arch cylinders (5) Boom cylinders (21) Secondary steering pressure switch (secondary steering arrangement) (22) Primary steering pressure switch (secondary steering arrangement) (25) Secondary steering pump and motor (if equipped) (26) Hydraulic pump assembly (27) Hydraulic tank and filter elements

The hydraulic system is a load sensing, pressure compensated, closed centered system. Hydraulic pump assembly (26) includes a pressure and flow compensator valve. The pump is located under the cab on the left side of the machine.

The hydraulic tank and filter elements (27) are located in front of the cab.

Decking blade cylinders (3) are located on each side of the machine at the front. Arch cylinder (4) and boom cylinder (5) is located on the rear of the machine.

Left steering cylinder (2) is mounted in the middle of the machine.

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Illustration 3	g00711087
Right Side of Machine (1) Brake control group (6) Tong cylinders (7) Rotator (8) Relief valve for the rotator motor (9) Right steering cylinder (10) Priority flow control valve (11) Steering valve (12) Decking blade valve (13) Pressure reducing valve (14) Arch control valve (15) Relief valve for the priority flow control valve (16) Differential lock control valve (17) Accumulator (pilot oil) (18) Boom control valve (19) Tong control valve (20) Rotator control valve (24) Pilot valve

Brake control group (1), priority flow control valve (10), steering valve (11), decking blade valve (12), pressure reducing valve (13) and relief valve (15) for the priority flow control valve are located in front of the cab on the right side of the machine. Access is gained by opening a cover.

Reference: For additional information on the braking system, refer to the Service Manual module Specifications, RENR4340, "525B & 535B Wheel Skidders, Braking System". Also, refer to the Service Manual module Systems Operation/Testing and Adjusting, RENR4341, "525B & 535B Wheel Skidders, Braking System" for the machine that is being serviced.

Pilot valve (24) is located at the rear of the cab on the right side of the machine. The accumulator and the differential lock control valve are located on a block manifold in the compartment with the pilot valve. Access is gained by opening a panel. Implement valves (14), (18), (19), and (20) are located above the rear axle.

Right steering cylinder (9) is mounted in the middle of the machine.

If the machine is so equipped, tong cylinders (6) are located on the grapple head at the rear of the machine. If the machine is equipped with a grapple rotator (7), rotator (7) is mounted in the grapple head at the rear of the machine. Relief valve (8) is located on the rotator motor.

Note: The 525B Wheel Skidder can be equipped with a three bank valve group. The valve controls the rotator, the tong, and the boom.

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Illustration 4	g00719689
Location of the Grapple Control Lever (28) Tong close (29) Grapple rotate counterclockwise (30) Tong open (31) Grapple rotate clockwise (32) Differential lock switch (33) Grapple control lever

Grapple control lever (33) is attached to multifunction pilot valve (24). Grapple control lever (33) is located on the right side of the cab next to the seat. The RAISE/LOWER function for the boom and the FORWARD and BACKWARD function for the arch are controlled by grapple control lever (33) .

Switches (28) and (30) for the grapple tong control are mounted in the grapple control lever. Switches (29) and (31) grapple rotator control are mounted in grapple control lever (33). Grapple tong control (28) operates the CLOSE function of the tong. Grapple tong control (30) operates the OPEN function of the tong. Grapple rotator control (29) and (31) rotates the grapple.

Differential lock switch (32) enables the differential lock for the axles.

Reference: For more information about the differential lock, refer to the Service Manual module Systems Operation, RENR4334, "Differential Lock" for the machine that is being serviced.

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Illustration 5	g00711096
Location of the Control Lever for the Decking Blade (34) Control lever (Decking blade).

Decking blade control lever (34) is located to the right of the steering wheel. Decking blade control lever (34) operates the RAISE/LOWER function of the decking blade.

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