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Hydraulic Body-Moti on Control SystemINFOID:0000000006256001
Shock AbsorberINFOID: INFINITI QX56 2011 Factory Service Manual
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Hydraulic Body-Moti on Control SystemINFOID:0000000006256001
Shock AbsorberINFOID:](/manual-img/42/57033/w960_57033-4368.png)
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Hydraulic Body-Moti on Control SystemINFOID:0000000006256001
Shock AbsorberINFOID:0000000006256002
The use of accumulator-generated pressure responsive to driving conditions or pressure generated by oil flow
to the upper/lower chamber improves the steering stabili ty at curving, in addition to the running performance
and a ride quality during off-road travel.
FRONT SIDE
Oil enters from oil inlet outlet hole (A) and flows into lower chamber (3) via outside oil path of cylinder inside.
Oil enters from oil inlet outlet hole (B) and flows into upper chamber (1). With the pressure difference between
oil flowed into the upper chamber and lower chamber, the piston (2) moves up and down and conveys a force
generated through this motion to the tires.
1. Middle tube assembly RH 2. Accumulator assembly RH 3. Front tube assembly A
4. Front tube assembly B 5. Accumulator assembly LH 6. PPMU pipe A
7. PPMU assembly 8. Middle tube assembly LH 9. PPMU pipe B
10. Rear tube assembly A 11. Rear tube assembly B
:Vehicle front
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REAR SIDE
Oil enters from oil inlet outlet hole (A) and flows into upper
chamber (1). Oil enters from oil inlet outlet hole (B)
and flows INFINITI QX56 2011 Factory Service Manual
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STRUCTURE AND OPERATION
REAR SIDE
Oil enters from oil inlet outlet hole (A) and flows into upper
chamber (1). Oil enters from oil inlet outlet hole (B)
and flows](/manual-img/42/57033/w960_57033-4369.png)
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REAR SIDE
Oil enters from oil inlet outlet hole (A) and flows into upper
chamber (1). Oil enters from oil inlet outlet hole (B)
and flows into lower chamber (3) via outside oil path of cylinder inside. With the pressure difference between
oil flowed into the upper chamber and lower chamber, the piston (2) moves up and down and conveys a force
generated through this motion to the tires.
PPMUINFOID:0000000006256003
PPMU stands for Passive Pressure Maintenance Unit.
System pressure increases according to increase of oil volume due to oil temperature increase. Sudden rise in system pressure can be controlled by feeding the increased oil into the PPMU.
Oil flows into oil chamber via PPMU pipe A and PPM U pipe B by influence of pressure change, pushes gas
spring of nitrogen gas, and pools.
1. Upper chamber 2. Piston 3. Lower chamber
A. Oil inlet outlet hole B. Oil inlet outlet hole
: Vehicle upper
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1. Upper chamber 2. Piston 3. Lower chamber
A. Oil inlet outlet hole B. Oil inlet outlet hole
:Vehicle upper
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When system pressure decreases, influent oil is dist ributed to both pipes by gas spring reaction force o INFINITI QX56 2011 Factory Service Manual
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When system pressure decreases, influent oil is dist ributed to both pipes by gas spring reaction force of
nitrogen gas via PPMU pipe A and PPMU pipe B to control sudden decrease in system pressure.
AccumulatorINFOID:0000000006256004
Influent oil from both front and rear shock absorbers on the outer ring flows simultaneously into the oil cham-
ber during cornering, and gas spring reaction force of ni trogen gas increases pressure, according to the influ-
ent oil level. As for inner ring side, the gas spring conv eys oil from the oil chamber to both front and rear shock
absorbers and decreases pressure, according to the oil level.
PPMU PipeINFOID:0000000006256005
PPMU and right and left tubes are connected. When oil in creases according to increase of system pressure,
increased amount of oil is sent to PPMU. When system pressure decreases, oil discharged from PPMU is sent
to right and left tubes.
1. Oil chamber 2. Bellows 3. Gas chamber
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1. Oil chamber 2. Gas chamber 3. Bellows
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SYSTEM
System DiagramINFOID:0000000006256006
System DescriptionINFOID:0000000006256007
Drivability during cornering and driving on rough road
is improved INFINITI QX56 2011 Factory Service Manual
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SYSTEM
SYSTEM
System DiagramINFOID:0000000006256006
System DescriptionINFOID:0000000006256007
Drivability during cornering and driving on rough road
is improved](/manual-img/42/57033/w960_57033-4371.png)
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SYSTEM
System DiagramINFOID:0000000006256006
System DescriptionINFOID:0000000006256007
Drivability during cornering and driving on rough road
is improved by mechanically generating oil pressure
by connecting 4 units of shock absor bers to front, rear, right, and left by piping lines of 2 systems.
Oil filling and system diagnosis can be performed using PPMU.
OPERATING PRINCIPLE
During cornering (Front and rear wheels in the outer side of corner: compressing)
When shock absorber in the outer side of corner is compressed during cornering, oil moves along piping path
and overflowing oil from piping path flows in accumulato r in the outer side of corner. Then, pressure increases
by action of gas spring of nitrogen gas acco rding to amount of oil that flows in.
Pressure in the inner side of corner decreases, since oil is discharged from accumulator by stroke (extending
direction) of shock absorber.
The pressure difference generates stabilizer-like action to maintain balance in vehicle posture for a steady
driving at cornering.
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During rough road driving (Front wheel LH: compressing, front wheel RH: extending, rear wheel LH: extending, rear
wheel RH: compressing)
Discharged oil from each shock absorber moves along piping
path, but oil does not overflow from piping path,
since oil moves in between each shock absorber. Oil does not flow in accumulator and system pressure does
not increase.
Since the oil from the contracted shock absorber flow s into the shock absorber upper chamber, stabilizer-like
action is not generated. This improves the adhes ion level and the running performance on rough roads.
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SYSTEM
Component Description
INFOID:0000000006256008
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Component parts Description
Needle valve A Needle valve for oil filling or trouble diagnosis. It is usually closed.
Needle valve B Needle valve for trouble diagnosis. It is usually open.
Needle valve C Needle valve for oil filling or trouble diagnosis. It is usually closed.
Needle valve D Needle valve for trouble diagnosis. It is usually open.
Needle valve E Needle valve for oil filling or trouble diagnosis. It is usually closed.
Relief valve If system pressure increases, then the orifice becomes clogged and oil flow into PPMU be-
comes disrupted, resulting in a large pressure difference between PPMU and both pipes. In
this case, the relief valve opens to let the oil flow.
Oil injection jack Oil filling inlet
For basic inspection use.
Air bleeder For air bleeding use.
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CAUTION:
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CAUTION:
Clean surrounding areas of oil inj ection jack using steam before starting operation, since there may
be mud on it.
Clean oil pressure gauge (special service tool: KV40108000) jack with steam before use.
1. Lift up the vehicle.
2. Remove protector of PPMU.
3. Remove cap of oil injection jack.
4. Install an oil pressure gauge (SST: KV40108000) (A) to oil injec- tion jack.
CAUTION:
Jack must be securely inserted until a click sound can be
heard.
Pressure reducing valve (B) of the oil pressure gauge
must be closed.
5. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations.
CAUTION:
Never loosen the needle valve more than required.
6. Refer to the figure and check the specified pressure.
7. Tighten needle valves A, C, and E of PPMU to the specified torque.
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Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
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8. Loosen pressure reducing valve (A) of oil pressure gauge and
then lower pressure.
CAUTION:
Be careful since oil drains swiftly from oil drain hole (B).
9. Check that reading of oil pressure gauge is 0 MPa.
10. Remove oil pressure gauge.
11. Install cap of oil injection jack.
12. Install protector of PPMU. Refer to SCS-39, "
PPMU, MIDDLE
TUBE ASSEMBLY, PPMU PIPE : Exploded View".
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