CAPÍTULO III. Causales Ilegales de los actos realizados por las autoridades fiscales
3.1 Ámbito de competencia de los actos realizados por las autoridades fiscales
3.1.4 Del Instituto Mexicano Del Seguro Social
3.1.4.5 Capítulo VI LIMSS
When the cycloid rotary valve and non reaction type steering gear, the oil inlet and return port are interconnected and two cavities of hydraulic cylinder are in close state. External force applied to hydraulic cylinder is transmitted to steering wheel but driver will not feel shaking from rough road.
Partial parameters of steering gear:
Max. operating pressure : 16 MPa Max. counter pressure : 6.3 MPa Constant counter pressure : ≤ 2.5 MPa Structure of steering gear
Structure of steering gear
For structure of steering gear, refer to page 4-6.
The components of the system are as follows.
Rotary
Rotary follow-up valve consisting of spool, sleeve and valve bodyfollow-up valve consisting of spool, sleeve and valve body
Controls direction of oil flow and its spool is directly connected with steering wheel and column.
Cyc
Cycloidal gear pairloidal gear pair (a stator and a rotor)
Detects motor to keep direct proportion between flow entering into steering cylinder and steering wheel angle as power steering and be the equal of hydraulic pump as manual steering.
Intermediate shaf
Intermediate shaft and yoke linking rotor and valve sleevet and yoke linking rotor and valve sleeve
Works to keep the valve sleeve synchronous with rotor as power steering while to transmit torque as manual steering.
Spr
Spring leafing leaf
Ensures the follow-up valve to return to center when not in steering.
One-way val
One-way valve between inlet and return portve between inlet and return port
As manual steering is made, this device allows the oil inside a chamber of steering cylinder to be pressed into another chamber through return port by the cycloidal gear pair while, as power steering is made, the device ensures that oil does not directly flow from P port into T port.
Port A and B are connected to two chambers of steering cylinder and port P connected to hydraulic pump and port T to oil tank.
Working principle of steering gear Working principle of steering gear
When steering gear is on center, the valve spool and sleeve are located in center by action of spring leaf. Flow from pump is directed to spool through two rows of small holes in valve sleeve and the end of valve spool and then is backed to oil tank through port T.
When the wheel is turned to right (or left), the spool is driven to turn to right (or left). Since there is a max. 10.5° turn between valve spool and sleeve, the spool has an angle of turn in reference to the sleeve, and the oil groove of spool is connected to oil inlet of sleeve. The flow from pump goes through valve sleeve, oil groove of spool, and further to rotor and stator from the sleeve to push the rotor to turn in reference to stator and, at the same time, the flow from rotor and stator goes through valve sleeve and is directed to a chamber of steering cylinder via port A (or B) to cause the piston rod extending (contracting) to push the steering wheel to turn to right (or left), while the flow in the other chamber of cylinder is directed to valve sleeve via port B (or A) and goes through the return groove of spool and then return groove of sleeve to return to oil tank through port T.
3)
Man
Manual steering :ual steering :
When engine stops or steering pump is malfunctioned, this type of steering gear allows turning of steering wheel manually by static pressure. When the steering wheel is turned to right (left), the valve spool turns for 10.5˚ to drive the sleeve, intermediate shaft and rotor by yoke. At the time, the stator and rotor work together as a pump. Rotation of rotor sucks oil out from port T and the flow goes through one-way valve, valve sleeve and spool, into inlet cavity of rotor pump. Manual turning of rotor pump pressurizes oil to make the flow to be directed to a chamber of steering cylinder to extend the piston rod (contract) causing the wheels to turn to right (left). Flow in another chamber goes via port B (A) through valve sleeve, spool, then is directed from the sleeve to inlet cavity of rotor pump through one-way valve, being constantly supplied to large (small) chamber to realize steering.
To guarantee realization of manual steering, the steering gear should not be mounted in a position 0.5 m higher than oil level of oil tank for better oil suction effect.
Using, disassembly and assembly Using, disassembly and assembly Using steering gear
Using steering gear Mounting
When mounting steering gear, be sure to keep in line with steering column (coaxial), and there should be a clearance axially to prevent the valve spool to become stuck. After assembly, check the steering wheel can return smoothly.
Oil line should be laid by marking of four ports: P is connected to pump, T to tank, A and B to left and right chamber of steering cylinder respectively.
Test operation
Before operation, clean the oil tank and refill to the max. level, loosen the steering cylinder screw connector, run oil pump in slow speed to bleed to the extent no foam is seen in out flowing oil.
Disconnect piston rod from steering arm, turn steering wheel to the left and right extremes (do not stop at two extremes) and refill oil into tank to the max. level again.
Fasten up all the screw connections (do not fasten under hydraulic pressure), connect piston rod to steering arm, check that system pressure meets the specified value as piston reaches extremes, check steering system works normally in any operating conditions and, when steering is not smooth, find out the reasons carefully, do not turn the wheel forcibly, nor disassemble the steering gear in a hurry to prevent parts to be damaged.
Using and Maintenance
Check oil leaks daily, oil level in tank and operation, replace filter element and drawing liquid.
When any problem is found, never turn the steering wheel by two people together.
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Disassembly of steering gear Disassembly of steering gear
Typically, there are two kinds of orders for disassembling a steering gear, i.e. solution A and solution B.
Front cover → small snap ring → bearing → large snap ring → valve spool & sleeve → yoke
→ spring leaf, rear cover → stop → stator → rotor → intermediate shaft → partition disc → steel ball → valve body.
Rear cover → stop → stator → rotor → intermediate shaft → partition disc → steel ball → valve spool & sleeve → yoke → spring leaf → small snap ring → bearng → large snap ring → front cover → valve body.
Notes in disassembly
Be careful not to make the working or end surface of any part to be damaged or scratched when disassembling. Do not put the rubber rings disassembled in gasoline to prevent from deformation or deterioration due to reaction with gasoline.
Assembly of steering gear Assembly of steering gear
Order of assembly: Valve spool → valve sleeve → yoke → spring leaf → large snap ring → bearing → small snap ring → valve body → front cover → steel ball → partition disc → intermediate shaft → rotor → stator → stop → rear cover.
Notes when assembling
Clean all parts with gasoline or kerosene before assembling (except for rubber ring). Paint on junction surfaces should be cleaned with acetone. Never use cotton fabrics or cloth to clean the parts, but use soft brush or silk. It’s the best to use compressed air to blow clean. After assembling steering gear, add 50~100 ml hydraulic oil via the oil filler, turn the valve spool to left and right and check if there is problem before assembling to the machine.
Junction surface of valve body, partition disc, stator and rear cover must be highly clean and there should no scratches or damages.
There is a mark each on the stator and shaft end and be careful to make correct assembly in the matching positions of shaft notch and internal hole of spline.
Conforming washer must be used for rear cover bolt.
When fastening 7 bolts for rear cover, fasten in order and every other two bolts, fasten up gradually to a torque of 4.1 ~ 5.1 kgf·m (29.7 ~ 36.9 Ibf·ft).
Port of P, T, A, B should must be connected in one-to-one correspondence.
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TROUBLESHOOTING TROUBLESHOOTING
Problem Cause Remedy
Oil leaks
Oil leaks Damaged O-ring at journal
and overflow valve.
Replace O-ring.
Oil leaks at connections of valve body, partition disc, stator and rear cover.
Clean off dirt on junction surface, grind scratches, and fasten up screws according to notes in assembly.
Steering is light under no load (or Steering is light under no load (or l i g h t l o a d ) b u t h e a v y w h e n l i g h t l o a d ) b u t h e a v y w h e n increasing load
increasing load
Pressure of overflow valve is lower than that of steering system or overflow valve is clogged.
Adjust the pressure of overflow valve to a specified value, or clean the overflow valve.
Steering is light as slowly turning Steering is light as slowly turning while heavy as fast
while heavy as fast
Insufficient oil supply of hydraulic pump.
Select a suitable pump. Check hydraulic pump for normal operation ad check if the volumetric efficiency is too little.
Steering is heavy as fast or slowly Steering is heavy as fast or slowly turning and no steering pressure.
turning and no steering pressure.
Malfunction of one -way valve inside the valve body.
If steel ball is missing, load ø8 steel ball. If steel ball is stuck by dirt, clean.
Foam is in oil, irregular sound is Foam is in oil, irregular sound is heard, cylinder moves and stops heard, cylinder moves and stops from time to time
from time to time
Air in steering system. Bleed air, check suction pipe for oil leaks, and that if return pipe is under oil level.
Steering is heavy
Steering is heavy Oil tank is not full, or oil viscosity too high.
Refill oil to specified level.
Use recommended fluid.
Severe steering deviation. Cylinder Severe steering deviation. Cylinder will not move as turning steering will not move as turning steering wheel (or moves slowly)
wheel (or moves slowly)
M alfun c t i o n in t wo -way buffer valve (steel ball is seized due to dirt, or spring failure).
Clean two-way buffer valve, or replace spring.
Disordered oil distribution. Steering Disordered oil distribution. Steering wheel turns itself or shakes
wheel turns itself or shakes
Reversed locations of rotator and intermediate shaft.
Reassemble referring to notes in assembly.
Obvious increase in vibration by Obvious increase in vibration by pressure. Further, the wheel could pressure. Further, the wheel could not turn
not turn
Broken or deformed yoke, broken or deformed opening of intermediate shaft.
Replace yoke, replace intermediate shaft. Substitution with other object is forbidden.
Steering wheel could not return to Steering wheel could not return to center. Steering gear could not center. Steering gear could not unload when steering wheel stops unload when steering wheel stops turning
turning
Steering column and valve spool are not coaxial.
Troubleshoot after finding out the cause.
Steering column has pushed the valve spool to be stuck.
Too much steering column rotating resistance.
Broken or deformed spring leaf.
Steering cylinder moves little at first Steering cylinder moves little at first and then will not as manual steering and then will not as manual steering
Too low oil level in oil tank ( oil in cylinder has returned
to oil tank).
Refill oil to specified level.
As power steering, cylinder piston As power steering, cylinder piston reaches the ex treme and driver reaches the ex treme and driver could not feel the extreme clearly.
could not feel the extreme clearly.
Steering cylinder will not move as Steering cylinder will not move as manual steering
manual steering
Too much radial or axial clearance at rotor and stator due to long time of use.
Replace rotor and stator. If axial clearance has become too large, grind the end surface of stator.
No manual steering
No manual steering Too high oil viscosity. Use recommended oil.
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