993K Wheel Loader Steering System Caterpillar

Steering System Pressure (High Pressure Stall) - Test and Adjust

Usage:

993K Z9K

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Personal injury or death can result from escaping fluid under pressure.
Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Always use a board or cardboard when checking for a leak.

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Personal injury or death can result from machine articulation or movement.
Machine frames can move and a person can be crushed.

Connect the steering frame lock link between the front and rear frames before working on machine.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat^® products. Dispose of all fluids according to local regulations and mandates.

Reference: For the correct procedure to relieve any hydraulic oil pressure that may be in the steering system, refer to the Service Manual module for Testing and Adjusting, "System Pressure - Release" for the machine that is being tested.

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Table 1
Required Tools
Part Number	Description	Qty
6V-3989	Fitting	1
6V-4143	Quick Connect Coupler	2
6V-8397	O-Ring Seal	1
6V-9508	Plug	1
6V-9828	Cap Assembly	1
8T-0860	Pressure Gauge	1
177-7861	Hose Assembly	1

Start the engine. Exercise the steering system in order to warm the hydraulic oil to normal operating temperature. Normal operating temperature can be monitored with the Advisor or with the Electronic Technician software.
After the oil has reached normal operating temperature, position the machine so that the machine is in the STRAIGHT AHEAD position.
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Illustration 1 g01376747

Steering Frame Lock in the LOCKED Position
Move steering frame lock to the LOCKED position. Engage the parking brake. Move the transmission direction selector to NEUTRAL.

Testing and Adjusting the Small Steering Pump

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Illustration 2	g01689697
(1) Pressure tap for the steering load signal line (2) Load sensing line for the large steering pump (3) Tee (4) Load sensing line for the small steering pump

Remove load sensing line (2) and place a cap over tee (3). Install 6V-9508 Plug and 6V-8397 O-Ring Seal onto load sensing line (2).
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Illustration 3 g01447523

Location for Pressure Taps

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Illustration 4 g01689719

Location for steering pump pressure tap
Install 177-7861 Hose Assembly and 8T-0860 Pressure Gauge to pressure port (10).
Start the engine and run the engine at high rpm. Move the STIC steering control lever to the LEFT TURN position or to the RIGHT TURN position. Continue to hold the STIC steering control in position until you are able to obtain a reliable pressure reading.
Record the pressure reading on the pressure gauge. The correct pressure should be 25000 ± 350 kPa (3600 ± 50 psi). If the pressure is incorrect refer to Step 5 through Step 6.
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Illustration 5 g01689698

Small steering pump
(11) Steering pump
(12) Pump control valve
(13) Locknut
(14) Adjustment Screw
The pump control valve (12) is located on the side of the steering pump (11). The steering pump is located behind the operator's cab.
When you are adjusting the small steering pump, loosen locknut (13). Turn adjustment screw (14) clockwise in order to increase the steering system pressure. Turn the adjustment screw counterclockwise in order to decrease the steering system pressure. Hold the adjustment screw in place and tighten the locknut.
Stop the engine. Lower the work tool to the ground.
Release pressure in the steering system.
Remove the hose assembly and the pressure gauge from the pressure tap.
Remove the cap, 6V-9508 Plug, and 6V-8397 O-Ring Seal. Connect load sensing line (2) to tee (3).

Testing and Adjusting the Large Steering Pump

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Illustration 6	g03326884
(1) Pressure tap for the steering load signal line (2) Load sensing line for the large steering pump (3) Tee (4) Load sensing line for the small steering pump

Remove load sensing line (4) and place a cap over tee (3). Install 6V-9508 Plug and 6V-8397 O-Ring Seal onto load sensing line (4).
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Illustration 7 g01447523

Location for Pressure Taps

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Illustration 8 g01689707

Location for Steering Pump Pressure Tap
Install 177-7861 Hose Assembly and 8T-0860 Pressure Gauge to pressure port (10).
Start the engine and run the engine at high rpm. Move the STIC steering control lever to the LEFT TURN position or to the RIGHT TURN position. Continue to hold the STIC steering control in position until you are able to obtain a reliable pressure reading.
Record the pressure reading on the pressure gauge. The correct pressure should be 31000 ± 750 kPa (4500 ± 110 psi). If the pressure is incorrect refer to Step 5 through Step 6.
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Illustration 9 g01689703

Large steering pump
(15) Steering pump
(16) Pump control valve
(17) Locknut
(18) Adjustment Screw
The pump control valve (16) is located on the side of the steering pump (15). The steering pump is located behind the operator's cab.
When you are adjusting the large steering pump, loosen locknut (17). Turn adjustment screw (18) clockwise in order to increase the steering system pressure. Turn the adjustment screw counterclockwise in order to decrease the steering system pressure. Hold the adjustment screw in place and tighten the locknut.
Stop the engine. Lower the work tool to the ground.
Release pressure in the steering system.
Remove the hose assembly and the pressure gauge from the pressure tap.
Remove the cap, 6V-9508 Plug and 6V-8397 O-Ring Seal. Connect load sensing line (4) to tee (3).