JLG 1850SJ Service Manual - Manual (Page 269)

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
3121619 – JLG Lift – 5-99
E NDCAP
1. Inspect endcap (34). Remove poppet (30) and spring
(31).
2. Check and record orientation of timing pin (27). Split in
timing pin should be face in or out of slot in valve plate.
3. Inspect poppet for wear on sealing face and replace if
necessary. Make sure spring is undamaged. Replace any
components if excess wear is present.
SERVO PISTON
Check servo piston assembly for wear or damage. Check corre-
sponding endcap bore for galling or excessive wear. Replace
piston if damaged.
HOUSING
Inspect housing is clean and free of foreign material. Inspect
swash plate bearing surfaces, and endcap mating surfaces.
SHAFT BEARINGS
Tapered roller bearing consists of a cup and cone. Make sure
cup and cone are free of excessive wear or contamination.
Rotate bearings to check for smoothness. If a contaminated
bearing is suspected, clean with a solvent and lubricate with
hydraulic fluid. Replace bearing if problem is not remedied by
cleaning. Inspect for uneven wear. If abnormal wear is found,
replace bearing.
Assemb l y
BEARINGS, SWASH PLATE, AND SHAFT
NOTE: If journal bearings are reused, reinstall in original orienta-
tion and position.
1. Coat journal bearings (7) with hydraulic fluid and install
in pump housing (11). Punch in retaining pins (7A) a
minimum of 0.002 in (0.5 mm) below bearing surface.
2. Reinstall shaft bearing cup (10) and cone (9).
3. Install three O-rings (1) on servo piston (2). Insert servo
piston through spring (3) and align hole with swash
plate (4) mounting holes. Secure with clevis pin (5) and
split ring (6).
4. Coat curved surface of swash plate (4) with hydraulic
fluid.
5. Reinstall swash plate assembly in original orientation in
housing.
6. Lubricate all sides of the servo piston and its bore liber-
ally with hydraulic oil. Rotate servo piston perpendicular
to swash plate, and at the same time compress bias
spring to fit into housing pocket.
7. Lubricate flat face of swash plate to prevent premature
wear during start-up.
27
30
31
34
Figure 5-130. Endplate Inspection
7
9
11
10
7A
Figure 5-131. Bearing Installation