5 . Insert the thrust ball (7) in the bearing of the head assembly (1). To hold the ball in position, place a
small amount of light grease inside the bearing.
6 . Place head assembly on frame and allow brushes to extend over commutator. Remove the string
securing the brushes in the holders. Push head assembly on frame and ensure proper indexing of
head and frame assemblies. Secure in place with thru bolts (4).
7 . Check freedom of rotation and end play (thrust) of the armature within the assembly. A minimum of
.005 of an inch end play is allowable. Should this be incorrect, adjust by adding or removing thrust
washers (11) on drive end of armature shaft, as required.
b . The valve body and gear case assembly (15) may be assembled to the reservoir (13) as follows:
1 . If removed, place the pump gears in the gear case and install cover. Install cover attaching bolts and
s e c u r e .
2 . Lubricate the reservoir seal ring (14) with hydraulic fluid (MIL-H-5606A) and place it in the recess
provided in the case (15).
3 . Position the valve body and gear case assembly (15) with the reservoir (13). Care should be taken
when lining up the armature drive with the pump gear. Do not run the motor to do this.
4 . Ascertain that the seal ring is properly positioned and install attaching screws. Tighten the screws so
that with the motor connected to a 14-volt source and with an ammeter in the circuit, the current
drawn does not exceed 12-amperes.
c . The base of the pump may be attached to the pump as follows:
1 . With the pump in the up-side down position, lubricate O-ring seals, and install in the recesses
provided in the valve body and gear case assembly (15).
2 . Install attaching bolts with washers and torque to 70 inch pounds.
3 . Safety attaching bolts with MS20995-C32 wire.
d . Conduct motor operational check not to exceed 10 seconds running time.
6-9. TEST AND ADJUSTMENT OF HYDRAULIC PUMP. (PRESTOLITE) (Refer to Figure 6-4.)
a . Test Equipment:
1 . Hydraulic pump and mounting base.
2 . Pressure gauge (0 to 1000 psi).
3 . Pressure gauge (0 to 3000 psi).
4 . Hoses with fittings to connect between base and gauges.
5 . Power supply (14 Vdc).
6 . Ammeter (0 to 100 amps).
7 . Fuse or circuit protector (100 amp).
b . Test and Adjustment:
1 . Connect a 0 to 1000 psi gauge to the low pressure port (port No. 3) of the pump base. (The low
pressure port, No. 3, is located nearest to the pipe plug installed in the base.)
2 . Connect a 0 to 3000 psi gauge to the high pressure port (port No. 1) of the pump base. (The high
pressure port, No. 1, is located farthest from the pipe plug installed in the base.)
3 . Connect the black lead of the pump motor to the negative terminal of the DC power supply.
4 . Fill the pump reservoir and bleed all air from the attached lines. (Lines may be bled by alternately
connecting the blue electrical lead and green lead to the positive terminal of the power supply until
all air is exhausted.)
5 . Connect the blue lead to the positive terminal of the power supply. Pump should operate and the high
pressure gauge should indicate 2250 +/-250 psi. (Should the pressure be incorrect, adjust valve “A”,
Figure 6-3, in pump reservoir. )
6 . Disconnect the blue lead and the high pressure reading should not drop more than 300 psi in five
minutes. High pressure may not be selected until after five minutes.
7 . Connect the green lead to the positive terminal of the power supply. Pump should operate in reverse,
dropping the high pressure gauge to zero and the low pressure gauge should indicate between 500 to
800 psi. When the green lead is disconnected, both pressure gauges should indicate zero psi. (Should
the pressure of 500 to 800 psi be incorrect, adjust valve “B”, Figure 6-3, in pump reservoir. )
Revised: 2/13/89
1H17
* CHEROKEE ARROW III SERVICE MANUAL
HYDRAULIC SYSTEM
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