JLG 40H Service Manual - Manual (Page 78)

SECTION 2 - PROCEDURES
2-58
– JLG Lift – 3120240
2.22 RACINE PROPORTIONAL AIR GAP
ADJUSTMENT.
NOTE: The assembly in Figure 2-31 includes select fit parts
in order to maintain a proper air gap. These parts
must remain as an assembly or if disassembled,
controlled to insure that these component parts are
not intermixed with similar parts.
NOTE: In the event that parts do become exchanged or you
suspect the air gap to be incorrect (Too much air gap
will result in loss of auxiliary power operation and
less than full spool shift; too little air will result in
erratic operation.), it may be checked and adjusted
using the procedure below.
a. *With all parts assembled as shown in Figure 2-
31, use a depth mike or other measuring instru-
ment to determine the distance from the end of
th e gui de t ube t o t he exp o se d en d o f t he
plunger. Record this dimension.
b. Remove plunger and poppet. With poppet
removed, install plunger and check distance
from the end of the guide tube to the exposed
end of the plunger.
c. Subtract the first dimension from the second
dimension, this will be the amount of air gap.
d. Correct air gap is.018"-.020" with.018" preferred.
If air gap is excessive, it may be reduced by
using a brass drift and hammer. Lightly tap end
of plunger with all parts assembled. Recheck air
gap.
e. If air gap is less than recommended, replace
nose cone assembly.
* All parts must be clean and properly assembled before
making these checks.
Figure 2-31. Racine Proportional Air Gap Adjustment, Machines Built Prior To Mid 1987.