1 | Steering limiter valve (left steering angle) |
2 | Steering limiter valve (right steering angle) |
3 | Tester |
3.1 | Switches |
3.2 | Display |
3.3 | Control wheel |
4 | Pressure limiting valve |
W46.25-1089-06
Danger | Risk of death caused by vehicle slipping or toppling off during lifting | Only lift vehicle at the lift support points specified by the vehicle manufacturer. | |
Warning | Risk of accident from vehicle starting off by itself when engine running. Risk of injury (bruises and burns) resulting from working on the engine while it is being started or when it is running. | Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts. | |
Warning | Risk of injury to skin or eyes from hydraulic fluid spraying out under pressure.Risk of poisoning from swallowing hydraulic fluid. | Depressurize hydraulic system completely before starting any work on it. Wear protective clothing and safety glasses. | |
Warning | Danger of injury to eyes caused by steering oil emerging at high pressure. Danger of poisoning caused by swallowing steering oil | The setting screws for the hydraulic steering limiters must be turned in by at least three rotations. Wear protective gloves, protective clothing and safety glasses. | |
Warning | Risk of injury from being trapped in the swivel range of steered axles | Ensure that no persons or objects are in the swivel range of all steered axles when turning the steering wheel. Do not stand in the swivel range of the additional steering axle when the engine is running. | |
Warning | Risk of injury to skin or eyes from hot hydraulic fluid spraying out under high pressure. Risk of burn injuries from contact with components heated by hot hydraulic fluid. Risk of poisoning from swallowing hydraulic fluid | Do not make any technical modifications to the pressure gauge or the test equipment. Check the pressure gauge and test equipment for mechanical damage each time prior to use. Observe the flow diagram when connecting the test equipment. Wear protective gloves, protective clothing and safety glasses. | |
Warning | Risk of accident and injury caused by diagnostic equipment in vehicle while traveling | Never use the test equipment to verify the delivery rate and oil pressure of the power steering pump or the pressure gauge while driving. | |
Warning | Risk of injury caused by body parts being pinched or crushed as cab is tilted | Ensure that no one is within the tilting range of the cab as it is being tilted. Always tilt the cab all the way to the end position and secure it with the safety strut. | |
Topical note | Special instructions for lifting and supporting vehicle | ||
Topical note | Notes on maintenance and repair work | ||
Topical note | Notes on handling test equipment for testing delivery rate and oil pressure of power steering pump | ||
Topical note | Notes on tilting the cab | ||
| Check | ||
1 | Install test equipment (3) in circuit 1. | ||
After bleeding, leave the propeller shaft and the drag links detached and the vehicle jacked up. Do not yet tilt back the cab. | |||
2 | Remove retainer and screw both steering limitation valves (1, 2) into steering gear up to end stop. | STEERING GEAR 765.887Steering limiter valve in steering gear center position for testing | |
HEMA dual-circuit power steeringSteering limiter valve in steering gear center position for testing | |||
3 | Tilt back cab. | Make sure that the test lines are not pinched. | |
4 | Start engine and run at idle speed. | ||
5 | Turn steering left or right several times using normal force of the hand until a steering gear oil temperature of approx. 50 °C is reached in the steering. | | |
6 | Turn steering wheel left up to mechanical end stop using normal force of the hand, read off pressure in display (3.2), and release steering wheel again. | | |
7 | Note down measured pressure. | ||
8 | Turn steering wheel to right up to mechanical end stop using normal force of the hand, read off pressure in display (3.2), and release steering wheel again. | | |
9 | Note down measured pressure. | ||
10 | Move front wheels to straight-ahead position. | ||
11 | Switch off engine. | ||
12 | Compare noted pressures with intended rated pressure. | The rated pressure is embossed onto pressure limiting valve (4). | |
STEERING GEAR 765.887Rated pressure (= governed pressure of pressure limiting valve in steering gear) | |||
HEMA dual-circuit power steeringRated pressure (= governed pressure of pressure limiting valve in steering gear) | |||
If both pressures are equally high and match intended rated pressure: | |||
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Look for cause of possible problems in power-steering pump or mechanical component parts (pressure limiting valve (4), seals in steering gear and, if applicable, auxiliary hydraulic cylinder are OK). | |||
If one of the two pressures is below the intended rated pressure, but the other pressure matches the intended rated pressure: | |||
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Remove hydraulic lines to hydraulic cylinder from steering gear or hydraulic cylinder, seal connections using suitable stop plugs so that a leakage in the hydraulic cylinder can be ruled out, and repeat test. | |||
For an M18x1.5 inside thread, use stop plugs with part number A 000 997 70 73. For other thread sizes, procure stop plugs commercially. The stop plugs must be designed for a pressure of approx. 200 bar. | |||
Union nut, steering gear oil line/hose | |||
If one of the two pressures is still below the intended rated pressure, but the other pressure matches the intended rated pressure: | |||
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Replace steering gear (4) (power-steering pump, pressure limiting valve and hydraulic cylinder can be ruled out as cause of problems). | |||
If both pressures are equally high and match intended rated pressure: | |||
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Replace hydraulic cylinder (steering gear can be ruled out as cause of problems). Then reconnect hydraulic lines to steering gear or hydraulic cylinder. | |||
Remove/install hydraulic cylinder of 2nd front axle | |||
Union nut, steering gear oil line/hose | |||
If both pressures are equally high, but deviate from the intended rated pressure: | |||
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Replace pressure limiting valve (4) and repeat test. | |||
STEERING GEAR 765.887Pressure limiting valve to steering gear | |||
HEMA dual-circuit power steeringPressure limiting valve to steering gear | |||
If both pressures are equally high after replacing the pressure limiting valve (4), but are below the intended rated pressure: | |||
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Check delivery rate and oil pressure of circuit 1 power-steering pump (in order to rule out defect in power-steering pump). | |||
If delivery rate and oil pressure of circuit 1 power-steering pump are OK: | |||
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Remove hydraulic lines to hydraulic cylinder from steering gear or hydraulic cylinder, seal connections using suitable stop plugs so that a leakage in the hydraulic cylinder can be ruled out, and repeat test. | |||
Union nut, steering gear oil line/hose | |||
If both pressures are still below the intended rated pressure: | |||
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Replace steering gear. | |||
If both pressures are equally high and match intended rated pressure: | |||
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Replace hydraulic cylinder (steering gear can be ruled out as cause of problems). Then reconnect hydraulic lines to steering gear or hydraulic cylinder. | |||
Remove/install hydraulic cylinder of 2nd front axle | |||
Union nut, steering gear oil line/hose | |||
13.1 | Turn steering to right. | On left-hand drive vehicles | |
Leave ignition switched on. | |||
13.2 | Turn the steering to the left. | On right-hand drive vehicles | |
Leave ignition switched on. | |||
14 | Attach drag link between 2nd steering idler arm and steering arm of 2nd front axle at 2nd steering idler arm. | ||
15 | Remove cable ties and attach drag link between steering gear and steering arm of 1st front axle at steering arm. | ||
16 | Move front wheels to straight-ahead position. | ||
17 | Position front wheels centrally on turn plates. | ||
18 | Adjust hydraulic steering limiter and install retainer with new spring lock washer. | ||
STEERING GEAR 765.887Adjustment pressure for steering limiter | |||
HEMA dual-circuit power steeringAdjustment pressure for steering limiter | |||
STEERING GEAR 765.887Steering limiter valve in steering gear center position for testing | |||
HEMA dual-circuit power steeringSteering limiter valve in steering gear center position for testing | |||
STEERING GEAR 765.887Retainer for steering limiter valves to steering gear | |||
HEMA dual-circuit power steeringRetainer for steering limiter valves to steering gear | |||
Steering test equipment | |||
19 | Remove test equipment (3) from circuit 1. | ||
20 | Raise vehicle at front axles, remove all turn plates, and lower vehicle back onto floor. | ||
21 | Conduct a road test. | During the test drive, check the overall steering ability of the vehicle. | |
22 | Check steering gear for leak tightness. | Visual inspection. |
765 589 01 21 00
Steering test equipment