SERViCE MANUAL
Paragraphs 24*27
With engine stopped,
use a
torque wrench
and ap-
ply 52 ft.-lbs. (70
N*m)
of
torque
to
the steering wheel
nut
in a
counterclockwise direction. Check the read-
ing
on the
test gage. Pressure reading should
be not
less than 55
psi
(380 kPa).
If
pressure reading
is not
correct, check
for the
following conditions:
1.
Wom
steering hand pump
or
damaged seals.
2.
Worn
or
stuck check ball
in
hand pump.
3.
Stuck check valve
in
pressure inlet port
of
hand
pump.
Then, with engine operating
at 1000 rpm,
turn
steering wheel counterclockwise
and
check pressure
gage reading. Pressure should read 2150
psi
(14825
kPa).
If
pressure reading is not correct, check
for
fol-
lowing conditions:
1.
Relief valve stuck
in
hand pump.
2.
Incorrect relief valve setting. (Paragraph
29).
Correct
the
problem
and
retest. Remove pressure
gage
and
connect steering hose
to
cylinder.
24.
STEERING CYLINDER
SEALS.
Ib
check steer-
ing cylinder seals, operate engine
at
low idle speed.
Turn steering wheel from lock
to
lock
at
least four
times
to
remove all
air
from
the
system. Turn wheels
fully to the left and stop the engine. Disconnect steer-
ing hose from left
end of
steering cylinder. Connect
a high pressure
cap on
steering hose. Allow
any oil
to flow from
the
open union
on
steering cylinder.
Start engine and operate
at
low idle speed. Check
for
oil leaking from open union and
at
the right steering
shaft seals
in end
cap.
A
small amount
of oil (up to
5 drops in 30 seconds) is permissible
for
leakage past
the piston seals. There should be
no
leakage
at
shaft
seals
in
end cap.
If
cylinder tests OK, repeat
the
test
on right
end of
cylinder.
25.
HYDRAULIC PUMP
Ib
check flow
and
pres-
sure
of the
hydraulic pump, first remove
the
plug
(30-Fig. 33)
for
the flow divider Remove spring (32)
and spool (33), then reinstall plug. Remove
the
pilot
relief valve
(29) and
install
a
test pilot relief valve
from test
kit
No. 399858R92. Disconnect
the
power
steering supply pipe (directly below hydraulic filter).
Cap
the
pipe
and
union
on
multiple control valve
with high pressure caps. Disconnect hitch supply line
(bottom rear line
on
multiple control valve)
and cap
the line. Connect
the
inlet hose from
the
flowmeter
to
the
hitch supply union
on the
multiple control
valve. Place outlet hose from flowmeter into trans-
mission oil fill hole and wire in place. Fully open load
valve
on
flowmeter. Start engine
and
operate
at a
speed
of
2180 rpm
for
Models 385 and
485,
2300 rpm
for Model 585
or
2400
rpm for
Models 685
and
885.
Record
the
flow. Close load control valve
to
obtain
a reading
of
2000
psi
(13790 kPa)
on
pressure gage,
then record
the
flow. Fully open
the
load valve
and
stop engine. The second flow reading must not be less
than
90
percent
of the
first flow reading.
If
second
reading is too low, check
for
the following conditions:
1.
Low oil
level.
2.
Clogged filter.
3.
Faulty pump.
Remove test pilot relief valve
and
using
new
seal
rings,
install original pilot relief valve. Remove flow
divider plug (30) and install spool (33) and spring (32).
Reinstall
and
tighten plug. Remove caps from steer-
ing supply line and union, then connect steering line.
Disconnect and remove flowmeter and connect hitch
supply line. Start tractor and bleed
air
from steering
system.
HYDRAULiC PUMP
Aii Modeis
26.
Tractors
may be
equipped with either
Sun-
strand
or
Plessy hydraulic gear type pumps. The max-
imum pump output
is
controlled
by
engine
rpm and
the number
of
teeth
on the
pump drive gear. Refer
to chart
in
Fig.
34 for the
model, engine test speed,
available drive gear teeth and maximum total pump
output. The priority flow divider sends approximate-
ly
3 gpm to the
steering system
and the
balance
is
used
for
the draft and position controls
on the
hitch
lift system
and for the
auxiliary control valves.
27.
R&R AND
OVERHAUL.
Ib
remove
the hy-
draulic pump, first drain all compartments
of
Hy-IVan
Plus fluid.
NOTE:
Aithough
the
pump can
be
removed with
left rear wheel instaiied, most mechanics prefer
to
remove ieft rear wheei
to
provide more room
to re-
move the muitipie controi vaive and pump assembly.
Thoroughly clean the area around the multiple con-
trol valve, then remove
the
hydraulic filter assembly
Tractor
Model
385
485
585
686
885
Engine Speed
RPM
2180
2180
2300
2400
2400
Drive Gear
Kk>.of Teeth
21
20
2t
20
23
20
23
20
23
20
Total Pump Output
U.S. Gals
15.6
t6.4
15.6
16.4
15.t
17.3
15.7
18.1
15.7
18.1
Litres
59.1
62.2
59.1
62.2
62.5
65.6
59.5
68.6
59.5
68.6
Fig.
34—Chart showing
engine test speed for
each
modei,
number
of
teeth avaiiabie
on
pump drive gear
and
maximum output
of
pump.
25
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