Skytrak 6042 Service Manual User Manual download pdf (Page 293)

8.61

Model 6042 Legacy Origin 7/02

Hydraulic System

Occasionally, fluid may seep, leak or be more forcefully

expelled from the filter head (Fig. 8-26, 11) when system

pressure exceeds the rating of the filter head or breather.

If the return filter becomes plugged, return hydraulic oil

will bypass the filter when pressure reaches 25 psi

(1,7 bar) and return to the reservoir unfiltered.

Carefully examine fluid seepage or leaks from the

hydraulic reservoir to determine the exact cause. Clean

the reservoir and note where any seepage occurs.

Leaks from a cracked or damaged reservoir require that

the reservoir be removed from the vehicle, flushed

completely with water and repaired by a certified welder

using approved techniques. If these conditions cannot be

met, the reservoir must be replaced in its entirety. Contact

OmniQuip or the nearest OmniQuip Sales and Service

Center (SSC) should reservoir welding or replacement be

required.

8.10.1 Hydraulic Reservoir Replacement

The fuel tank and the hydraulic reservoir (Fig. 8-26, 1

and 2) are one unit and are removed together. Refer to

Section 7.8.2, “Fuel/Hydraulic Oil Tank” for information

on the fuel tank/hydraulic reservoir removal. Support the

fuel tank/hydraulic reservoir with a suitable device. Loos-

en, but DO NOT remove, the hex nuts (10) on the car-

riage assemblies. Slide the unit to the left to allow the

carriage bolt heads to come through the slots in the

frame.

Install the replacement fuel tank/hydraulic reservoir

(Fig. 8-26, 1 and 2) sliding the carriage bolt assemblies

into the slots in the frame. Slide the unit to the right and

secure it to the vehicle by tightening the hex nuts (10).

8.11 HYDRAULIC SYSTEM PUMP

The gear pump (Fig. 8-27) is attached to the transmission

and driven by the pump main shaft by meshing with an

internal transmission gear.

Figure 8-27 Gear Pump

The pump draws fluid through a 2" inside diameter hose

via negative displacement.

Fluid is forced from the pump through a 3/4" inside

diameter hose to the unloader valve. Hydraulic system

pressure begins at the pump. Various factors are involved

in creating the relatively high pressure used in the hydraulic

system. Pump rpm, controlled via a transmission input

shaft (and dependent on engine rpm), the internal pump

gears and passageways and the differential between

pump inlet (2" I.D.) and outlet (3/4" I.D.) openings, all

contribute to pressure supplied to the unloader valve. The

unloader valve ultimately regulates maximum system-

operating pressure of 3,000 psi (207 bar) for various

vehicle functions.

8.11.1 Pump Failure Analysis

The pump is the “heart” of the hydraulic system, and

when there is a problem in the system, the pump often is

blamed. Yet, pump failure is seldom due to failure of

pump components. Pump failure usually indicates

another problem in the hydraulic system.

According to pump manufacturer statistics, 90-95 percent

of pump failures are due to one or more of the following

causes:

• Aeration

•Cavitation

• Contamination

• Excessive Heat

• Over-Pressurization

• Improper Fluid

In the event of pump failure, investigate further to

determine the cause of the problem.

DANGER: NEVER weld in, on, near or

around the hydraulic reservoir. Hydraulic fluid

and fumes can cause the reservoir to explode.

This can result in death or serious personal

injury.

MT1690

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