Westinghouse 5026 Instruction Pamphlet page 34

66
CROSS COMPOUND Am COMHU]SSORS
erly maintained, as it not only greatly decreases the
air delivered, but the faster .eed required increases
the heating, and it also causes ~ounding through loss of
cushion. When tightening the packing, do not bind the
rod, as to do so will damage both the packing and the
rod. Be careful not to cross the gland nut threads.
With two compressors per engine, the separate throt­
tles should be kept wide open and the speed regulated
by the main compressor throttle. The purpose is to
equally divide the work.
If necessary to replace a broken air valve on the
road or elsewhere not permitting of proper fitting, at the
earliest opportunity have the repairman replace the tem­
porary valve with another so as to insure the correct
angle and width of valve and seat contact, the needed
ground joint and the proper Hft. The standard lift for
all valves of the 8Y2" compressor is 3-32 of an inch;
for the 10%" compressor, 5-32 of an inch for the suc­
tion and discharge valves and
%
of an inch for the inter­
mediate valves. When the combined wear of the valve
and seat increases this lift more than
1'«
of an inch, the
seat is liable to be injured and the valve broken, with
consequent annoyance and delay. For the purpose of
readily determining the lift of air valves, an Air Valve
Lift Gage, as illustrated in Figs. 25, 26 and 27, may be
purchased from us.
To determine the lift of the upper air valve, the gage
is first applied to the top flange of the air cylinder, as
illustrated in Fig. 25, and the sliding arm adjusted until
its end rests against the top of the stop on the air valve,
in which position it is locked bv means of the thumb nut.
MAINTENA:'>ICE
67
With the arm thus locked, the gage is applied to the
valve cap, as illustrated in }'ig. 26, and if the valve has
proper lift, the under side of the collar of the valve cap
will just rest upon the shoulder of the sliding arm, as
illustrated. If the gage arm fails to touch the stop on
the valve when the shoulder on the sliding bar rests
upon the face of the collar, the valve has a lift greater
Fig. 26
Fig. 27
than standard by an amount equal to the distance be­
tween the gage arm and the stop. If this lift is greater
than the maximum permissible, a repair valve having
a long stop should be substituted for the old valve and
the stop lowered until the standard lift is reached, a'5
indicated by the gage.