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Hydraulic machinery: analysis of common failure causes of full hydraulic steering system

2020-07-25 09:03:22
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he connecting part of the oil pump to ensure that the oil pump connection is firm and reliable.


1.3 Manpower steering check valve failure


There is no manual steering check valve; the check valve steel ball and valve seat are not tightly sealed; the check valve steel ball falls between the valve sleeve and the valve body ring groove; the check valve spring is damaged.


The above reasons can cause the one-way valve to be not closed tightly during power steering, and the oil inlet and outlet ports are connected. Check to make sure the check valve is installed correctly; check whether the oil is clean. Clean the steering gear; check the sealing condition of the one-way valve steel ball and valve seat. If the seal is not tight, it can be repaired by grinding, and then replaced with a new steel ball.


1.4 Steering gear safety valve failure


The steering gear safety valve setting pressure is too low; the steering gear safety valve spring is damaged; the steering gear safety valve seat is not tightly sealed; the steering gear safety valve body is damaged.


The above reasons can cause the safety valve of the steering gear to fail and open in advance. Check the setting pressure of the safety valve, the sealing condition of the valve seat, and whether the spring is deformed or failed. If the spring force is insufficient, a gasket can be added between the spring and the spring seat.


1.5 The valve core and valve sleeve are deformed, causing them to be stuck.


When installing the machine, add a small amount of hydraulic oil to the oil inlet. The spool should be flexible to rotate. If there is jamming, it should be ground. Sometimes, when tightening the bolts at the bottom of the steering gear, the force is uneven, and the valve core may jam. The correct method is to tighten the bolts evenly at intervals of 2-3 times.


1.6 Steering mechanism failure


The tire pressure is insufficient; the steering knuckle and the king pin are too tight or lack of oil; the steering knuckle thrust bearing is lacking or damaged; the front beam and the frame are deformed and the front wheel positioning is misaligned; the longitudinal and transverse tie rods are adjusted too tightly or Lack of fuel; the kingpin’s rearward tilt is too large, the kingpin’s inward tilt is too large or the front wheel is negatively tilted: these can cause the driver to feel heavy and laborious when turning the steering wheel to the left or right, without a sense of return; When turning at low speeds or turning around, it is very difficult to turn the steering wheel, or even unable to move. Elimination measures: ensure that the tire pressure is normal; the steering knuckle and the king pin are tightly matched and well lubricated; the steering knuckle thrust bearing is intact and there is no shortage of oil; the front beam and frame are not deformed; the front wheel is well positioned.


2. Analysis of the causes of steering wheel deviation and troubleshooting measures


2.1 The positioning spring between the valve core and the valve sleeve in the steering gear is damaged or too soft, so that the valve sleeve cannot automatically return to the neutral position. At this time, the positioning spring must be replaced.


2.2 The movement of the valve sleeve is blocked due to oil contamination. Clean the valve sleeve to make the valve sleeve move flexibly.


2.3 The valve sleeve is not in the middle position due to the offset of the valve sleeve and the valve core step position. Disassemble and overhaul the valve sleeve and valve core, and replace if necessary.


2.4 The flow control valve is stuck, which causes the oil pressure of the oil pump to be too high, causing the pressure difference between the left and right chambers of the steering cylinder to be too large. Disassemble and repair the flow control valve.


2.5 The seal of the one-sided steering cylinder is damaged. Disassemble and repair the steering cylinder seal.


2.6 The two front tires have different air pressures or different diameters. Check and adjust the tire pressure.


2.7 The deflection of the left and right front leaf springs is different. Check and adjust the deflection of the leaf spring, and replace the steel plate if necessary.


2.8 The front and rear axles or the frame are bent in the horizontal plane. Check and correct the distortion.


2.9 The wheelbases on both sides of the frame are not equal. Adjust and make sure the wheelbase is equal.


2.10 The tightness of the two front wheel hub bearings or hub oil seals is different. Check the bearing or oil seal.


2.11 The wheels at both ends of the front and rear axles have unilateral braking or unilateral drag. Check and adjust the braking conditions of the wheels.


2.12 The camber angle, caster angle or kingpin inclination angle of the two front wheels are not equal.


2.13 Toe is too large or negative toe. Check and adjust the toe.


2.14 The road has a large degree of camber or has lateral wind.


3. Analysis of the causes of different degrees of left and right steering and troubleshooting measures


3.1 The valve core of the steering gear deviates from the middle position, or although it is in the middle position, it is inconsistent with the gap between the valve sleeve shoulder. Check to make sure that the shoulder is well sealed and the spool is in the middle position.


3.2 There is a dirt block between the valve core and the valve sleeve, which makes the resistance different when moving left and right. Disassemble and clean the steering gear to ensure that the hydraulic oil is clean.

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3.3 Improper adjustment of the adjusting nut. Check and readjust the nut.


3.4 The reasons that cause the steering wheel to deviate can also cause the difference in the lightness of the left and right steering when the vehicle is driving.


4. Analysis of the reason why the steering wheel feels heavy when turning fast and troubleshooting measures


4.1 The oil pump drive device sometimes fails.


The drive belt is slipping or the drive gear (key) is worn. Check the oil pump part, adjust the belt tension, repair or replace the drive gear (key).


4.2 The connection of the oil pump is faulty. If the connecting bolt of the oil pump is loose or missing, check the connecting part of the oil pump to ensure that the oil pump connection is firm and reliable.


4.3 Flow control valve failure. The spring of the flow control valve is too soft or leaking seriously, resulting in insufficient oil supply during sudden steering. Check the flow control valve and replace if necessary.


4.4 The safety valve fails or leaks seriously. Check the safety valve and replace if necessary.


4.5 Excessive wear of the oil pump and serious internal leakage. Check the working condition of the oil pump, repair or replace the oil pump.


4.6 The oil pump is incorrectly selected, resulting in insufficient oil supply. Replace with a suitable oil pump.


5. Analysis of the cause of noise during steering and troubleshooting measures


5.1 The oil tank is short of oil or the oil tank is insufficient, and the oil pump is easy to suck in air when it is working. Remedy: Check the liquid level of the fuel tank and add enough hydraulic oil.


5.2 The oil seal of the shaft head of the oil pump is damaged, and the oil pump is easy to suck in air when it is working. Replace the shaft end oil seal.


5.3 The oil pump drive device sometimes fails. The drive belt is slipping or the drive gear (key) is worn. Check the oil pump part, adjust the belt tension, repair or replace the drive gear (key).


5.4 When the low-pressure pipeline is damaged or the pipe joint is loose, air will enter the system when the oil pump is working. Check the low-pressure pipeline to ensure that the low-pressure pipeline and pipe joints are not leaking.


5.5 The filter is clogged. Elimination measures; check, clean or replace the filter element.


5.6 The inner holes of the inlet and outlet pipes are blocked. Cause the oil pump to suck oil difficult or unable to suck oil. Clean the oil inlet and outlet pipelines.


5.7 Excessive wear of the oil pump and serious internal leakage. Check the working condition of the oil pump, repair or replace the oil pump.


6. Analysis of serious causes of steering wheel shaking and troubleshooting measures


6.1 The wear between the connecting pin and the connecting pin seat increases the gap. Check the gap and replace the connecting pin and the connecting pin seat if necessary.


6.2 The steering wheel bearing is damaged. Replace the bearing.


6.3 There is air in the steering cylinder. Loosen the oil port connector on one side of the oil cylinder and turn the steering wheel to fill the cavity of the steering oil cylinder where the joint is not loosened by the steering gear. Tighten the joint until the loosened joint does not emit bubbles and only flows through the oil.


7. Analysis of the causes of front wheel head swing and troubleshooting measures


7.1 The front wheel rotation quality (including tires, rims, brake drums or discs, wheels, etc.) is unbalanced. Remedy: Check and ensure that the front wheel rotating parts are in good dynamic balance. Replace corresponding accessories if necessary.


7.2 The radial circle or end circle runout of the front wheel is too large. Elimination measures: correct or replace the corresponding accessories.


7.3 The front wheel uses retreaded tires or the tire pattern is inconsistent or the degree of tire wear is different. Elimination measures: When assembling tires, the tires assembled on the same vehicle should be guaranteed to use tires of the same brand, structure and performance. If this is not possible, tires of the same brand, specification, pattern and type should be assembled on the same axle; tires with the same rim diameter and different widths cannot be mixed; radial tires and bias tires cannot be mixed; section Tires with different widths should not be mixed; when replacing new tires, they should be replaced on the whole vehicle or on the same axis; tires with directional patterns should be installed in the specified rolling direction.


7.4 The camber of the front wheel is too small; the kingpin has a negative caster or the caster angle is too large; or the toe is too large. Elimination measures; check and adjust to make the "three tilts and one beam" within a reasonable range.


7.5 The kingpin inclination or caster angle of the two front wheels is inconsistent.


7.6 The ball joints of the longitudinal and transverse tie rods are connected loosely. Elimination measures: repair or replace the tie rod end.


7.7 The front wheel hub bearing is loose. Elimination measures; adjust or replace bearings.


7.8 The front suspension shock absorber fails or the effectiveness of the left and right shock absorbers is too different. Elimination measures: adjust or replace the front suspension shock absorber.


7.9 The front suspension height or stiffness of the left and right frames (leaf springs are expressed in terms of thickness, length, number of sheets, arc height, or newness and oldness) are too different. Elimination measures: adjust or replace the leaf spring.


7.10 The front leaf spring U-shaped bolt is loose or the leaf pin and bushing fit loosely. Elimination measures; tighten bolts or replace bushings.


7.11 The movement of the steering system and the front suspension interfere with each other. Elimination measures: check and adjust so that the steering system and the front suspension do not interfere with each other.


7.12 The front beam or frame is bent or twisted. Elimination measures; correct front beam or frame.


7.13 When the road unevenness is too large, and the impact frequency of the road surface on the wheels is consistent with the natural frequency of the front beam angular vibration, under the influence of the gyroscope effect, it will cause the front wheel to swing.


8. Analysis of the reasons why the steering wheel rotates and cannot return to the neutral position and troubleshooting measures


This failure occurs when the steering gear is repaired or reassembled after the steering gear is disassembled for maintenance. The relative positions of the valve core and the valve sleeve are installed incorrectly, causing the steering gear oil distribution relationship to be disordered. Reassemble the coupling so that the mark on the coupling spline is aligned with the mark on the rotor spline.


9. Reason analysis and elimination measures of no dead point in steering wheel rotation


9.1 The two-way cushion valve in the steering gear fails. Check the two-way cushion valve to make the valve core and valve seat tightly combined.


9.2 The piston sealing ring of the oil cylinder is damaged. Replace the oil cylinder piston sealing ring.

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Liaoning Chengxiang Hydraulic Machinery Manufacturing Co., Ltd

Business manager phone:13470397782    Office phone:0419-7148218ext.802     mailbox:slcxjx@163.com


Business office phone:0419-2621118    Technical business phone:0419-7148218ext.805    address:Shaling Town, Taizihe District, Liaoyang City

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