KPM RCVD8C Series User manual

PILOT VALVE
RCVD8C SERIES
INSTRUCTION MANUAL
COPY
JOB NO.
NOTE
1.DRAWN (02360-8776,02360-8928)
控DATE : 2004.11.30
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CHECKED
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FILING NO. DRAWING NO.00115869
00115869-1_RCVD8C_manual.doc (TOTAL PAGES)
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Contents
Chapter 1 Safety information --------------------------------------- Page 1
Chapter 2 Overview ----------------------------------------------- Page 5
Chapter 3 Specifications --------------------------------------- Page 5
Chapter 4 Operation ----------------------------------------------- Page 6
Chapter 5 Maintenance ----------------------------------------------- Page 10
Chapter 6 Troubleshooting and corrective measures --------------- Page 30
Pilot valve cross-section --------------------------------------- Page 31

Chapter 1 Safety information
1. About this operation manual
To operate this equipment safely and correctly, read this manual carefully and understand it
thoroughly before handling and operating the equipment. Specifically, be sure to read "Safety
precautions" for correct use of this equipment.
Always keep this manual accessible in a safe place.
2. Safety precautions
Before using this equipment, read this "Safety precautions" carefully for correct use.
Those precautions will help you and others use this equipment safely and correctly, and avoid
personal injury or damage to the equipment. Each precaution, with expected results of incorrect
usage, is grouped into "Caution" or "Warning" depending on the severity and urgency of the injury
or damage. Be sure to follow the precautions because of their importance in safety.
!Warning: Indicates a potentially hazardous situation that, if not avoided, could
result in death or serious injury.
!Caution: Indicates a hazardous situation that, if not avoided, could result in
minor injury or damage to property only.
1

2.1 Precautions in operating the equipment
Pay attention to the following points when you operate this equipment.
!Warning
(1) Before starting this equipment, carefully check if there is no one or no obstacle within the
danger zone near the operating range of the equipment.
(2) If you find the equipment operating in a dangerous condition, urgently turn off the pressure
source.
(3) If an abnormal condition (e.g. strange sound and oil leakage) happens, urgently stop the
equipment and take a necessary action to prevent possible damage and injury.
Caution
!
(5) Before starting this equipment for the first time, verify that the hydraulic circuit and the
electric wiring is correct, and tightened portions do not become loose.
(6) Do not use the equipment without satisfying the specifications stipulated in the external
dimension drawing.
(7) During operation, the equipment may become high temperature due to the heated hydraulic
oil or for other reasons. Take care not to touch the equipment to prevent possible burns.
(8) Use only the specified hydraulic oil, and control the degree of contamination to the
recommended value. Otherwise, the equipment may malfunction or become damaged.
(9) Be sure to install such a filter at the inlet of the equipment that is shown in the external
dimension drawing.
2.2 Precautions in handling the equipment
Pay attention to the following points when you handle the equipment.
Caution
(1) To prevent possible injury, wear protective devices as necessary.
(2) Depending on the weight of the equipment or your work posture, your hand may be caught
or you may suffer from a lower-back pain. Pay attention to your work posture.
(3) Do not step on, beat, drop, or apply external force to the equipment. Otherwise, a
malfunction, damage, or oil leakage may happen.
(4) If oil is spilled on the floor, wipe it out. Otherwise, you may drop the equipment or may be
injured slipping on it.
!
2.3 Precautions in installing or removing the equipment
2

Caution
(1) Before starting operation, be sure to turn off the power to the equipment and verify that
motors and engines, etc have been stopped. Also, verify that the pressure inside the
hydraulic piping is zero (0). To release remaining pressure from inside the accumulator
circuit, operate the lever of the equipment several times (at least 10 times).
(2) Operations such as installation and removal of equipment, piping, and wiring must be done by
persons who have expert knowledge. (Person who has expert knowledge: Class 2 Oil
pressure adjustment technician or equivalent person, or a person who has received a service
training of our group.)
(3) Clean the mounting holes and mounting surfaces. Otherwise, bolts may become loose or
seals become broken, resulting in equipment damage or oil leakage.
(4) When mounting the product, be sure to use specified bolts and tighten them with the torque
specified. Otherwise, malfunction, damage, or oil leakage may happen.
!
2.4 Precautions in maintaining and storing the equipment
Caution
(1) Users do not modify the product.
(2) Do not disassemble or reassemble the product without our permission. Otherwise, the
product may not be able to function as specified, resulting in a failure or accident. If
disassembling/reassembling is absolutely necessary, only a person who has expert
knowledge should do that. However, as stated in 2.5, we can guarantee the performance and
functions of only those products that have passed our outgoing performance and operation
inspection.
(3) When the product is transported or stored, keep it from dust or corrosion, paying attention to
ambient temperature and moisture.
(4) Before the product is started after a long time of storage, the seals may need to be replaced.
!
3

2.5 Precautions relating to performance and functions
Caution
Since this product is critical safety equipment, we can guarantee the performance and functions
of only those products that have passed our outgoing performance and operation inspection.
Take this fact into account before starting disassembling/reassembling the product.
!
3 Exemption from responsibility
Be aware that we are not responsible for the following.
(1) Force majeure, such as natural catastrophe, or external causes such as accidents
(2) Wrong use or misuse
yUse of the equipment for the purposes not intended
yUse of the equipment in the conditions not specified
yExecution of prohibited operations
yExecution of operations (handling, maintenance, and check sequence) not specified in the
operation manual
yFailure to perform operations (handling, maintenance, and check sequence) specified in the
operation manual
(3) Unsafety operation
(4) Performance or functions of the equipment after disassembled/reassembled by you or a third
party.
4

Chapter 2 Overview
The damper-embedded pilot valve, RCVD8C, is a reducing-type valve using 4
secondary-pressure-controlling reducing valves contained in a single valve casing. The outlet
pressure varies according to the angle of the operating section. The RCVD8C also includes a
damping mechanism coupled to the valve casing, a mechanism which prevents hunting
(lever-hunting) in the man-machine system.
In addition to a damping mechanism, the RCVD8CC also includes shuttle valves which select and
output higher pressure from secondary pressures.
Chapter 3 Specifications
Maximum primary pressure 9.8 MPa {100 kgf/cm2}
Secondary pressure 0-4.4 (maximum control pressure) MPa
{0-45 kgf/cm2}
Allowable back pressure At maximum O.29 MPa {3 kgf/cm2}
Rated flow volume 10 L/min
Operating angle ±12.4°
Mass Approx. 7.8 kg per set
Piping For favorable response, the internal diameter
and the length of the pipe should be approx. φ8
and 3 m respectively. To prevent an effect of the
back pressure, return the return oil to the tank
directly.
Filter To prevent the spool from being stuck, install a
40-mesh or more filter at the inlet of the P port.
5

Chapter 4 Operation
The damper-embedded pilot valve includes in its main body a damping function to prevent hunting
(lever hunting) in the man-machine system.
The following explains the operation of the damper-embedded pilot valve, separating it into 2
sections: "a. reducing valve" and "b. operation section damping mechanism" based on the hydraulic
circuit diagram below, the assembly cross-section drawing in 31(RCVD8C), 32(RCVD8CC), and the
damping operation explanation drawing in 9. The following figure shows a typical usage of the pilot
valve.
⑦
①Pilot valve ③Main pump ⑤Hydraulic motor
②Pilot pump ④Control valve ⑥Hydraulic cylinder
⑦Shuttle valve(RCVD8CC only)
Hydraulic circuit diagram
1. Reducing valve section
1.1 When the pilot valve operating section is at the neutral position
The spool (301), pushed upward by the return spring (335), washer 1(215) through the
spring seat (311), is at its neutral position as shown in the assembly cross-section drawing.
Since the outlet port is joined only with the tank port T as a result of the spool switching
function, the pressure at the outlet ports 1 and 2 is the same as the pressure at the tank port
T.
1.2 When the pilot valve operating section is tilted from the neutral position
6

As shown in the assembly cross-section drawing, when the cam (420) is rotated clockwise,
the push rod (214) at the port 1 is pressed downward, which pushed the spool downward
with the help of the washer 1, the spring seat, the secondary-pressure-setting spring (324),
the washer 2 (217), and the washer 3 (313). As a result, the port P and the port 1 are joined
each other and the oil supplied from the pilot pump starts to flow into the port 1, generating
a flow pressure.
When the pressure at the port 1 increases to a pressure equivalent to the force of the
secondary-pressure-setting spring, having been set by the tilted operating section, the oil
pressure applied to the spool and the spring force are kept in balance, which keeps the port
1 outlet pressure constant.
Since the spool at the port 2 remains neutral, the return oil from the control valve flows out
through the tank port T.
Depending on the specifications, the push rod touches the top of the spool directly when the
operating section is tilted fully, which forcefully pushes down the spool, joining the port P
and the outlet port, resulting in an equal pressure at both ports.
2. Operation section damping mechanism
2.1 When the operating section is at the neutral position
As shown in the assemble cross-section drawing, the push rod is pushed upward by the
damping spring (336,337) through the piston (224).
2.2 When the operating section is tilted from the neutral position (Refer to the damping
operation explanation drawing (1))
As you see in the drawing, when the cam is rotated clockwise, the push rod at the port 1 is
pressed downward and the piston moves downward.
At this moment, the oil in the damping piston chamber passes out through the orifice in the
piston, producing a pressure used for damping.
On the other hand, the push rod at the port 2 is moved upward by the damping spring
through the piston.
At this moment, the oil in the tank room is absorbed into the damping piston chamber
through the 3 ball check valve portions (using the ball (225) and the bush(223)). The oil
outside the piston chamber flows through the path that joins with the port T at the top of the
casing.
2.3 When fully tilted operating section is tilted in reverse direction (Refer to the damping
operation explanation drawing (2))
In the operation explanation drawing, if the cam, having been fully tilted clockwise, is tilted
anticlockwise, the push rod at the port 2 is pushed downward and the piston moves
downward. At this moment, as in the case above, the oil inside the damping piston passes
out through the orifice in the piston, producing a pressure used for damping.
On the other hand, the push rod at the port 1 is moved upward by the return spring (335)
7

and the damping spring.
As in the case above, the oil in the tank room is absorbed into the damping piston chamber
through the 3 ball check valve portions (using the ball (225) and the bush (223)). The oil
outside the piston chamber flows through the path that joins to the tank port from the
casing top.
In other words, the damping force is generated in both cases when the operating section is
tilted from the neutral position to the fully tilted position and from the fully tilted position to
the neutral position.
3.Shuttle valve section (RCVD8CC only)
3.1 When the operating section is at the neutral position
The secondary pressure ports are both the same as the tank port T, so the shuttle valve
outlet port is also the same as the tank port T.
3.2 When the pilot valve operating section is tilted from the neutral position
When the one secondary pressure port generate the pressure, the ball(192) is pressed to
the other secondary pressure port and closed the port. The shuttle valve outlet port pressure
is the same as the one secondary pressure port. In other words, the higher secondary
pressure is selected and output from the shuttle valve outlet port.
8

(⇒Operation direction)
The oil inside the piston
chamber passes out through
the orifice.
The pressure generated at
this moment is used for
damping pressure
The oil outside the piston
chamber flows through the
pass that joins to the tank port
at the top of the casing.
(⇒Operation direction)
T
P
(2)<Lever stroke state and the operation
when the lever is tilted in reverse direction>
Full stroke
oil
1 (3)
neutral
2 (4)
The oil in the T line
is absorbed into the
damper room
through the 3 ball
check valve
portions.
The damping force is
generated in both
directions
If the lever is tilted in
reverse direction from
⇒to →, the left
piston immediately
acts as a damper
p
iston
When the lever is tilted from the
neutral position to the reverse
position, the push rod is pushed
upward by the damping spring
(⇒Operation direction)
Damping operation explanation drawing
Orifice
Push rod
Piston
When the lever is
tilted from the
neutral position
toward
direction, the oil
in the right (left)
piston chamber
passes out the
orifice.
Piston chamber
(1)<Operation when the lever is tilted from the neutral position>
T
P
1 (3)2 (4)
9

Chapter 5 Maintenance
1. Special jig for disassembling/reassembling
(1) Special jig 1 (for removing and pressing the bush)
Center hole allowed (φ2 or less)
(2) Special jig 2 (for fitting the locking ring)
10

2. Disassembling instructions
1) Operational precautions in general
(1) Prepare a solid and rattle-free working bench that is wide enough to place parts on and that
does not allow the parts to drop or move.
(2) Prepare tools and materials.
(3) Since the parts are very precise, handle them with much care not to bump them each other or
drop them.
(4) Do not hit or wrench the parts even when they are hardly moved. Otherwise, burrs may be
generated or the parts may be damaged, causingan oil leakage or degradation in performance.
Always work with patience with much care.
(5) Leaving the parts disassembled may cause them to rust as a result of humidity or contamination.
If it is absolutely necessary to stop working before reassembling, pay attention to prevent rust
and dust.
2) Disassembling procedures
No. Work Photo or Figure
1 Clean the pilot valve with kerosene.
yClose each port with a blind plug.
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
2 Fix the pilot valve on a vice using cushion
sheets.
Remove the pedal cover (521) from the pedal
(520)
11

No. Work Photo or Figure
3 Unscrew the Allen screw (522) with an Allen
wrench. Remove the pedal (520).
4 Unscrew the Allen screw (473) with an Allen
wrench. Remove the block (431).
5 Remove the bellows (501) from the cover (201)
by pulling the bellows upward.
6 Loosen the setscrew (423) with an Allen
wrench.
yBe carefulbecause Loctite #241 is applied
to the setscrew and the tightening torque
is large.
12

No. Work Photo or Figure
7 Putting a round bar (φ8 or less) on one end of
the cam axis (413), tap the bar gently with a
hammer to pull out the axis.
8 Remove the cam (420) as an assembly with the
setscrew (471) and lock nut (472) attached.
yNote down the positional relationship
between the cam and the cover (201).
yBe careful because the push rod (214)
may push out while the cam is removed.
Caution
9 Unscrew the Allen screw (271) with an Allen
wrench.
10 Remove the cover (201).
yNote down the positional relationship
between the cover and the casing (101).
yBe careful because the push rod (214)
and the plug (202) may be pushed out by
the damping springs (336, 337) while the
cover is removed. (The plug remains
inside the casing as a result of the friction
of the O-ring (212) only.)
Caution
13

No. Work Photo or Figure
11 Pull out the push rod from the plug.
yNote down the positional relationship
between the plug and the push rod.
yTake care not to scratch the push rod
surface.
yBe careful because the plug may be
pushed out while the push rod is
removed.
Caution
12 Remove the plug with the grease cup (203),
NHU packing (210) and O-ring (212) attached.
yNote down the positional relationship
between the plug and the casing.
yBe careful because the piston is pushed
out by the damping spring while the plug
is removed.
Caution
13 Remove the piston (224).
yNote down the positional relationship
between the piston and the hole in the
casing.
14 Remove the damping springs (336, 337) from
the casing.
yNote down the positional relationship
between the damping spring and the hole
in the casing.
14

No. Work Photo or Figure
15 Remove the spring seat (218) from the casing.
yNote down the positional relationship
between the spring seat and the hole in
the casing.
16 Remove the steel ball (225) using a device,
such as a magnet.
yTake care not to lose the steel ball.
17 Remove the locking ring (221) from the casing
using pliers.
yNote down the positional relationship
between the locking ring and the hole in
the casing.
yBe careful because the bush may be
pushed out by the return spring (335)
while the locking ring is removed.
yTake care not to damage the casing inside
surface.
Caution
18 Take the bush (223) out of the casing using
tweezers.
yNote down the positional relationship
between the bush and the hole in the
casing.
15

No. Work Photo or Figure
19 Remove the reducing valve section assembly
and the return spring (335) from the casing.
yNote down the positional relationship with
the casing hole.
20 Place the cover (201) with its side downward on
a flat table. Putting the special tool 1 on the
bush (412), tap the tool with a hammer to pull
out the bush.
21 Fix the cam assembly on a vice, untighten the
lock nut (472) with a spanner then remove the
lock nut and setscrew (471).
yIf setscrew replacement is not required,
handle the setscrews as part of the cam
assembly thereafter since neutral position
adjustment is required when setting up
the cam assembly.
16

No. Work Photo or Figure
22 To dismantle the reducing valve section
assembly, stand upright the spool (301) bottom
end on a flat work bench, push down the spring
seat (311) then remove 2 semicircular washers
1 (215) using a small flat-head screwdriver tip.
yTake care not to scratch the spool surface.
yDo not lower the spring seat by more than
4 mm.
23 Remove the spool (301), spring seat (311),
secondary-pressure-setting spring (324),
washer 2 (217) and washer 3 (313).
yTreat the parts as an assembly until they
are installed.
yThe washer 2, whose thickness varies
depending on the spool assembly, is for
adjustment to preset the
secondary-pressure-setting spring.
However, in some cases, the washer is not
used.
24 Remove the grease cup (203) from the plug
(202).
25 Remove the NHU packing (210) from the plug
using a small flat-head screwdriver or the like.
yTake care not to scratch the internal
surface of the plug.
17

No. Work Photo or Figure
26 Remove the O-ring (212) from the plug.
27 Fix the Casing (101) on a vice using cushion
sheets. Unscrew the Plug (153) with an Allen
wrench.
(RCVD8CC only)
28 Pull out the Seat (191) from the Casing (101).
(RCVD8CC only)
29 Remove the Steel ball (192) from the Casing
(101).
(RCVD8CC only)
18
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