Case 648 Loader-Backhoe Loaders Service Manual

 ——— ;_ —_—
5 me
POWER STEERING
FOR MODEL 648
Service Manual 9-51520
;
|
|
Printed in U.S.A.
TABLE OF CONTENTS
Introduction ........ viii i ee 2
Specifications ........._—._e_eceeeerecerrrecorerevero 2
How lt Works and Oil Flow Diagrams............. 4-11
Troubleshooting and Testing the
Power Steering System ..................... 0c... 12-13
Removal and Installation of Power
Steering Components .......ñ.o_eweoxreeoranaranenen. 14
Disassembly, Inspection and Assembly of
Power Steering Components ......... —ec__ecreeeeceoo 15-19
10-80-SL-2000
INTRODUCTION
This service manual section covers the full time
hydro static power steering system used in the
Model 648 Loader and 648 Loader-Backhoe.
Pump supply oil for the power steering system
comes from the loader bucket control valve outlet
port to the power steering control valve inlet port.
Return oil from the power steering control valve
return port tees into the return line upstream of
the return line filter screen.
Relief valve protection for the power steering
system is provided by the attachment lift relief
valve located in the travel control valve.
The power steering control valve directs oil to and
from the manual pump and steering cylinder.
SPECIFI
Relief Valve ........e.eceeoererecrccrvra er NY era
ravel control valve.
(Attachment lift relief valve) Loc
The manual pump is turned by the steering wheel
and is a positive displacement gerotor, bi-directional
pump. The manual pump provides steering control
and operational! flow and pressure through the
power steering contro! valve to the steering
cylinder.
If the engine is stopped, the tractor can be steered
by increased manual effort. A check valve in the
power steering control valve is provided to allow
this feature.
also increase if either the
loader bucket circuit is held
or if the engine is operated
Steering effort will
attachment lift or
against the relief va
at reduced RPM.
O
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QF
6.5 GPM (24 I/m at 3000 engine RPM and
1500 PSI (10 300 kPa)
1550 + 50 PSI (10 700 + 300 kPa) at 3600 engine RPM.
SAE 20W-40 Motor oil
Off ee о, a nvarederanrernverereaneereranecoeoen.. API Service Classification SE or CC
Toe In rome DS eee aaa 1/8" to 3/8 (3.2 mm to 9.5 mm) toe in.
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HOW IT WORKS AND OIL FLOW DIAGRAMS
RIGHT TURN - ENGINE RUNNING
RESERVOIR AND PUMP
Whenever the engine is running the hydraulic
pump operates continuously, drawing oil from the
reservoir. The oil is directed to the steering control
valve by first passing through the backhoe or PTO
valve if so equipped, the travel control valve and
loader bucket control valve. The attachment lift
relief valve protects the power steering system
from excessive pressure.
MANUAL STEERING PUMP
The manual steering pump, in a right hand turn,
pressurizes oil from three stator and rotor cavities
through three holes in the pump body into three
holes in the commutator. The oil then passes from
the three holes through the center of the com-
mutator to the rearward cavity and out through the
right hand port to the control valve.
CONTROL VALVE
The pressurized oil from the manual pump R. H.
port enters the front inlet port of the valve. This
pressurized oil moves the spool rearward uncovering
passages which permits oil from the hydraulic
pump to pass through the spool and out the rear
valve port. The oil then enters the L. H. port of
the manual pump. The manual pump increases this
hydraulic pump pressure and directs it to and
through the control valve to the front port to the
power steering cylinder.
The pressurized oil is directed to and retracts the
power steering cylinder, turning the wheels in a R.
H. turn. Return oil being displaced from the power
“turns, through the rear steering
passages in the control valve and
oil cooler and reservoir.
FROM TO
| STEERING CYLINDER STEERING CYLINDER
TO MANUAL ||: AE! FROM MANUAL
PUMP | PUMP
SOOO СЯ
JU po —
ream iE E L - A
e ЛЫ >. Cay Mu | PR res ; Pg rT pas
Ge
© [BALL CHECK SEATED
AGAINST STOP FL
Ч CONTROL
| TO RESERVOIR A VALVE
LOADER
BUCKET 6
VALVE
A STEERING
>” CONTROL VALVE
>
Re, CYLINDER
RETURN TO
RESERVOIR
Æ] HYDRAULIC PUMP SUPPLY
EN MANUAL PUMP PRESSURE
El RETURN OIL FIGURE 2 RIGHT TURN - ENGINE RUNNING
В” че
LEFT TURN - ENGINE RUNNING
RESERVOIR AND PUMP
Whenever the engine is running the hydraulic
pump operates continuously, drawing oil from the
reservoir. The oil is directed to the steering control
valve by first passing through the backhoe or PTO
valve if so equipped, the travel control valve and
loader bucket control valve. The attachment lift
relief valve protects the power steering system
from excessive pressure.
MANUAL STEERING PUMP
The manual steering pump in a left hand turn,
pressurizes oil from three stator and rotor cavities
through three holes in the pump body into three
slots on the commutator. The oil then passes from
the three slots to the forward cavity and out
through the L. H. port to the control valve.
CONTROL VALVE
The pressurized oil from the manual pump L.H.
port enters the rear inlet port of the valve. This
pressurized oil moves the spool forward uncovering
passages which permits oil from the hydraulic
pump to pass through the spool and out the front
valve port. The oil then enters the R. H. port of
the manual pump. The manual pump increases this
hydraulic pump pressure and directs it to and
through the control valve to the rear port to the
power steering cylinder.
The pressurized oil is directed to and extends the
power steering cylinder, turning the wheels in a
L. H. turn. Return oil being displaced from the
power steering cyknder returns through the front
steering cylinde tand passages in the control
valve and r the filter, oil cooler, and
reservoir.
TO
STEERING CYLINDER
FROM
STEERING CYLINDER
FROM MANUAL |} 5
PUMP |
a
Li ve a,
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STEERING It
CONTROL Er:
VALVE TO RESERVOIR — PUMP
A
AGAINST STOP
BALL CHECK SEATED
LOADER
BUCKET LS e
VALVE 24507
050
|
fe
7
> CYLINDER
RETURN TO
w RESERVOIR
ED HYDRAULIC PUMP SUPPLY
EN MANUAL PUMP PRESSURE
:
|
|
= RETURN OIL FIGURE 3 LEFT TURN - ENGINE RUNNING
gy.
RIGHT TURN - ENGINE NOT RUNNING
MANUAL STEERING PUMP
The manual steering pump, in a right hand turn,
pressurized oil from three stator and rotor cavities
through three holes in the pump body into three
holes in the commutator. The oil then passes from
the three holes through the center of the
commutator to the rearward cavity and out through
the R. H. port to the control vaive.
CONTROL VALVE
in the
inlet and outlet
from the manual
Static oil from the hydraulic pump exists
control valve hydraulic pump
passages. The pressurized oil
pump R. H. port enters the front inlet port of the
valve. This pressurized oil from the manual pump
moves the valve spool rearward uncovering pas-
sages which permit pressurized oil to enter and
pass through the front port to the power steering
cylinder.
This pressurized oil is directed to and retracts the
power steering cylinder, turning the wheels in a
R. H. turn. Return oil being displaced from the
power steering cylinder returns through the rear
steering cylinder port, ball check and the spool to
the rear valve port. The oil is then returned to the
L. H. port of the manual pump.
FROM
STEERING CYLINDER
TO MANUAL au
PUMP
REARWARD
AGAINST STOP
3 2
TO RESERVOIR e
LOADER
BUCKET
VALVE
e EN MANUAL PUMP PRESSURE
E RETURN OIL
EN STATIC OIL
TO
STEERING CYLINDER
AN FROM MANUAL
El PUMP
UNSEATED
~~ STEERING
ONTROL
VALVE
RETAINER RING e
=>;
A @ STEERING
>. A CONTROL VALVE
RETURN TO
RESERVOIR
FIGURE 4 RIGHT TURN - ENGINE NOT RUNNING
04
LEFT TURN - ENGINE NOT RUNNING
MANUAL STEERING PUMP
The manual steering pump, in a left hand turn,
pressurizes oil from three stator and rotor cavities
through three holes in the pump body into three
slots on the commutator. The oil then passes from
the three slots to the forward cavity and out
through the L. H. port to the control valve.
CONTROL VALVE
Static oil from the hydraulic pump exists in the
control valve hydraulic pump inlet and outlet
passages. The pressurized oil from the manual
-10 -
pump L. H. port enters the rear inlet port of the
valve. This pressurized oil from the manual pump
moves the spool forward, uncovering passages
which permit pressurized oil to enter and pass
through the rear port to the power steering
cylinder.
This pressurized oil is directed to and extends the
power steering cylinder, turning the wheels in a
L.H. turn. Return oil being displaced from the
power steering cylinder returns through the front
steering cylinder port, ball check and the spool to
the front valve port. The oil is then returned to
the R. H. port of the manual pump.
SPOOL MOVED
FORWARD
AGAINST STOP
E 7 BALL CHECK
FROM POWER UNSEATED
PUMP
CONTROL “E
VALVE TO RESERVOIR
VALVE PORT
SP,
E
er
LOADER
BUCKET
VALVE
STEERING
@& CONTROL VALVE
RETURN TO
RESERVOIR
EN MANUAL PUMP PRESSURE
| RETURN OIL
Ш STATICOIL FIGURE 5 LEFT TURN - ENGINE NOT RUNNING
> 17 в
TROUBLESHOOTING AND TESTING THE POWER STEERING SYSTEM
SYMPTOM: EXCESSIVE STEERING EFFORT REQUIRED
CAUSE
CORRECTION
. Engine operating at reduced RPM.
1. Increase engine speed.
. Hydraulic oil cold.
2. Operate unit to warm hydraulic oil,
. Operator attempting to turn the steering wheel
too rapidly.
3. Turn steering wheel at a normal rate of speed.
. Operator holding travel circuit, attachment lift
circuit or loader circuits against relief while
attempting to steer.
4. Release or feather other controls to prevent
relief valve from opening while attempting to
steer.
reducing power to
NOTE: Relief valve will ~open
other circuits ering wheel is held
against its stop.
ENS
. Suction line restriction (travel, lift and bucket 5. Confirm wi meter test and remove
circuits would also be affected.) restriction
©
. Main hydraulic pump efficiency loss (travel, lift 6. Conf N flow meter test and repair or
and bucket circuits would also be affected).
hydraulic pump.
. Power beyond O-ring in travel control valve
leaking (bucket circuits would also be affected). A
a
>
r
-
au power beyond O-ring.
N
. Controi Valve sticking or binding.
2)
Remove valve. Clean and flush contamination
from valve and system. Remove burrs or
scratches from spool with crocus cloth.
Q
NN
CORRECTION
1. Control Valve sticking.
1. Remove valve. Clean and flush contamination
from valve and system. Remove burrs or
scratches from spool with crocus cloth.
2. Valve end cap worn.
2. Replace valve end cap.
.12-
SYMPTOM: EXCESSIVE STEERING WHEEL SLIP.
CAUSE CORRECTION
1. Cap cylinder ports at valve. If slip is reduced,
repair cylinder.
1. Leaking cylinder piston.
2. Cap cylinder ports at valve as in “1” above. If
slip remains excessive isolate valve from manual
pump as follows.
Run engine at 3,600 RPM and apply 6 ft. Ib. (8.2
Nm) of input torque to steering wheel. Record
wheel slip in RPM. Stop engine and apply 6 ft. Ib.
2. Leaking control valve or manual pump. (8.2 Nm) of input torque to steering wheel. Record
wheel slip in RPM.
If wheel slip remains
repair or replace th
becomes less with
igh with engine stopped,
al pump. If wheel slip
stopped, replace the
control valve, Q
NOTE: ‚ Сета wheel slip is normal and
Y n
NN dicate a defect in the system.
(СХ
NV
> SYMPTOM: STEERING WHEEL TURNS FREE. O
ÓN
CAUSE | os ED) CORRECTION
NS
N 1. a. Fill reservoir to correct level. Consult your
© operator’s manual.
b. Turn steering wheel full right to full left
со several times to purge air from system.
1. Air in hydraulic lines.
(2
2. Steering wheel loose om 2. Install key and tighten steering wheel nut.
Ca
>
3. Input shaft broken. 3. Replace input shaft.
SYMPTOM: WRONG RESPONSE TO STEERING WHEEL
CAUSE CORRECTION
1. Hoses to steering cylinder connected wrong. 1. Reverse hose connections at steering cylinder.
- 13 -
COMPONENT REMOVAL AND INSTALLATION
MANUAL PUMP
REMOVAL
INSTALLATION
1.
7.
. Remove the rear access panel.
Remove the tubes between the manual pump
and the control valve. Cap or plug the ports of
the valve, pump, and tubes to prevent dirt
entry.
Carefully remove the steering wheel center cap
by prying at the two locking tabs.
Remove the steering wheel.
Remove the collar from the steering shaft by
pulling upwards.
Remove the cotter pin which secures the attach-
ment lift control lever to its lower support.
Remove the link to the lift spool from the lift
control lever.
Pull the attachment lift lever up to clear the
working area.
Remove the four bolts that secure the manual
pump to the instrument panel.
Position the manual pump with the w
facing forward. <
Loosely install the four mounting bc O)
Install and tighten the tube) N
manual pump and control RES
Tighten the four mounti
Connect the attachment Ni##lever.
Install the steering shaft collar, steering wheel
and cap.
Install the rear access panel.
CONTROL VALVE
REMOVAL
1.
2.
Remove the rear access panel.
Remove the battery and battery tray. Tag the
wires to insure proper reconnection.
Remove the cotter pin which secures the attach-
ment lift control lever to its lower support.
&
-14 -
4. Remove the link to the lift spool from the lift
control lever.
5. Remove all hoses and tubes connected to the
control valve. Cap or plug the ports to prevent
dirt entry.
6. Remove the three bolts holding the control valve
to the frame.
7. Remove the valve through the access panel
opening.
INSTALLATION
1. Install the control valve through the access panel
opening with the cylinder ports to the left and
the inlet and outlet ports to the right.
2. Loosely install the three mounting bolts.
3. Loosely install a esyand tubes to the control
valve.
4. Tighten and tubes and the three
mo
e attachment lift lever.
< the battery tray and battery.
Ne, the rear access panel.
STEERING CYLINDER
REMOVAL
1. Turn the front wheels to the full left hand turn
position,
2. Remove the front ball joint from the left
spindle.
3. Remove and plug (to prevent dirt entry) the hy-
draulic lines from cylinder ports.
4. Rernove the rear shoulder bolt from the cylinder.
5. Remove the cylinder.
INSTALLATION
1. install the cylinder with the work ports facing
upward.
2. Install the rear shoulder bolt and front ball
joint.
3. Install the hose from the rear of the control
valve to the piston end of the cylinder.
4. Install the hose from the front of the control
valve to the rod end of the cylinder.
>
DISASSEMBLY, INSPECTION AND ASSEMBLY OF COMPONENTS
STEERING CYLINDER
DISASSEMBLY
1. Secure the cylinder in a vise at the piston end
mounting bracket. To prevent damage to the
cylinder, do not place the body of the cylinder
(9) in the vise.
2. Use a spanner with 1/4 inch (6.35 mm) dowels
on 2 inch (50.8 mm) centers to loosen the
gland (3).
3. Remove the gland (3).
4. Pull the rod and piston (6) from the body (9).
5. Remove the seals (8, 7, 5, 4, 2) and wiper (1).
INSPECTION
Clean all parts before inspection. Inspect the rod,
piston, and cylinder body for nicks, scratches, or
burrs. Remove nicks, scratches, or burrs with a
crocus cloth,
Replace the necessary components if damage is
severe.
- 15 -
ASSEMBLY
1.
2.
FIGURE 6 STEERING CYLINDER
. Install the
с a
Install o-ring (7) onto the piston.
Warm piston seal (8) to insure that it is pliable.
Install piston seal (8) onto the piston on top of
o-ring (7).
Lubricate the piston and rod (6) with a small
amount of 20W-40 motor oil.
. Insert piston and rod (6) into cylinder body (9).
Use care not to damage the piston seal (8) on
the cylinder body (9) threads.
. Install the rod seal (2) inside the gland (3). The
wide skirt of the seal (2) must face the piston
ring (4) and o-ring (5) onto
the gland
er (1) to the gland (3) with the
end facing outward.
In he
the gland and tighten securely using the
er spanner.
MANUAL STEERING PUMP
DISASSEMBLY
1. Clamp the manual steering pump in a vise with
steering wheel shaft pointing down. This will
prevent the internal parts of the pump from
falling out.
2. Unbolt the end cover (17) and remove. Mark the
stator (14) and rotor (13) with an indelible
marking pencil for proper installation.
(15),
3. Remove the spacer (16), seal stator (14),
rotor (13) and spacer plate (9).
4. Remove lower drive link pin (10), commutator
(8), drive link (7) with upper link pin (6) and com-
mutator drive pin (5).
(4), (2)
5. Remove steering shaft thrust bearing
and thrust washer (3).
6. Remove the pump from the vise and remove the
rubber water seal (24), felt bushing (23), and
snap ring (22).
7. Remove and discard the retainer washer (21),
spacer (if so equipped), backing ring (20) and
seal (19) (0 ring or cup type).
8 Remove the bearing (1) by pressing from the
steering wheel end of housing with the lower
machined face of the housing setting on a block
of wood.
Clean all parts before inspection bein SS y! not
to damage any machined surfaces. G
Inspect all machined su r abnormal wear,
scratches and scoring. ished pattern on the
spacer plate (9) and end plate (17) due to rotor
action is normal.
INSPECTION
Check the thrust bearing (2)
looseness.
Check the rotor (13) to stator (14) clearance using a
narrow feeler gauge (refer to inset E) the clearance
should not exceed .007 inch (.13 mm).
Check the rotor (13) to stator (14) thickness (inset
D) with a micrometer or dial indicator. |f rotor
thickness is more than .002 inch (.05 mm) less
than thickness of the stator (14) replace stator and
rotor.
Inspect rotor vanes and springs as indicated in
Figure 7. Refer to inset B and C.
©
- 16 -
Check the clearance between the large end of the
steering shaft (4) and the body (26), it should not
exceed .006 inch (.15 mm). Replace the part that
shows the most wear.
ASSEMBLY
1. Install new bearing (1), by pressing against the
hardened end of the bearing shell on which the
number appears, into the body from the rotor
end to a depth of 3-27/32 inches (97.5 mm)
(refer to inset A).
2 Install new thrust bearing (2) and thrust washer
(3) onto shaft (4). Coat the shaft area above the
thrust bearing with_No. 2 Moly Disulfide grease
to displace any dir Xrom being locked in the
cavity in the hoti&! en pump is reassembled.
3. Install th
driveali )
4), commutator drive pin (5),
ith upper link pin (6).
She commutator (8) and install it with
otary motion, engaging the drive pin
==
nstall the spacer plate (9) and lower drive link
pin (10).
6. Install the rotor (13), stator (14) aligning original
marks, new seal (15) and spacer (16).
7. Install the end cover (17) and tighten the bolts
(18) to 18 - 22 foot pounds (25 - 29 Nm) of
torque.
8. Install new teflon backed oil seal (19), new
backup ring (20) and new retainer (21). Install
these parts only far enough into the pump body
to allow the snap ring (22) to be installed.
These parts can only be bought in the seal kit.
9. Install snap ring (22), with rounded edge toward
retainer (21), felt bushing (23) and water seal
(24).
NOTE: In some hand pumps the spacer between
the retainer and backup ring was used in
production pumps. Do not reinstall this
spacer when installing seal kit which has
teflon backed oil seal.
10. Lubricate the pump by filling one port with
clean oil and turn the steering shaft until oil
appears at the other port.
INSET C WORN FLAT INSET E
ALONG THIS
9” XT |
, | I~ ‚250” (6.35 mm)
N |” MINIMUM
(2
.002” (05 mm) LESS
THAN ROTOR WIDTH
REPLACE WHEN “A” 15 .002” (.05 mm)
SMALLER THAN В’
INSET A
777
un
SE}
Y INSET B ®
у
Пе Ni |
. N „о
je 3-27/32" (97,5 mm} —| -080” TO .100” (2.03 TO 2.54 mm)
| N
FIGURE 7 MANUAL STEERING PUMP
- 17 -
STEERING CONTROL VALVE
DISASSEMBLY
1. Mark the end caps (10) and body (8) for proper
installation.
2 Remove the end caps (10) and ‘’O’’ rings (9).
3. Slide the valve spool (7) out of the centering
spring (5) end of the valve body (8).
4. To remove the centering spring assembly (5),
insert a small rod in the cross drilled hole in
the spool (7) and a small rod in the centering
screw shank (6). Unscrew the centering screw
from the valve spool. Be careful not to damage
the valve spool. Remove the washers (4) and
centering spring (5).
5. Remove the ball check plug (3), 10” ring (2)
and 1/4’ ball (1) from the body.
INSPECTION
Clean all parts before inspection. Inspect the valve
spool (7) and body (8) bore for nicks, scratches or
burrs. If valve spool or body is damaged, complete
valve must be replaced.
Inspect ball check (1) and seat for cracks or nicks.
OF
К
Ss
Inspect the centering spring (5) for cracked coils.
The spring should be replaced if it does not meet
the following specifications.
Free Length ..........eeerreoveanoo 860" (21.84 mm)
Active Coils.......ec_eccrrcervrrerecr rene 0e 00 6
Wire Diameter.....o—.rrereomrecneore: 080” (2.03 mm)
Compressed Length
.824'" (20.93 mm)
2 Pounds Pressure
uv = =: = OEA
Replace all ‘’O’’ rings, lubricate all parts with oil.
ASSEMBLY
1. Install ball check (1), new “0” ring (2) and
plug (3).
2. Install centering washers (4) and spring (5) on
crew (6) into valve spool
foot pounds (20 Nm).
)
¿bool {7) into the centering spring
4. Ins valve
ong ot alve body (8). Make sure the spool
e
ly in the body.
Gon new end cap 0” rings (9) and end caps
, aligning original marks. Torque bolts to 14
e
(10)
to 17 foot pounds (19 - 23 Nm).
- 18 -
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