OP-755 Part 2 Pages 197-401 - Personal Page of GENE SLOVER

312
as whenusing "Ser'vo Electrical" control, however
if the stopping is not normal for these
methods of operation the probable causes will
be the same as when using !!Servo E'l.e ct.r-Lc aL"
control, except for the limi t switch adjus tments.
An additional reas on for inaccuracy,
will be an improperly adjusted latch and vent
valve cam. This will prevent the brake from
applying, and the circuit from venting, when
the powder car reaches the loading or unloading
stations.
96. Ratchet slips when hoisting.
(a) This will be recognized by a clicking sound in
the B-end, while the unit is hoisting or starting
to hoist. The reason for this is that the
brake is slow in releasing due to one of the
following causes.
(1) Too much travel of the brake cylinder piston.
Check the location of the end piston
274318-1 to be 3 inches from the face
of the brake cylinder head.
(2) Too little clearance between the brake band
and the brake drum when the brake is released.
Check the clearance between the brake
band and the drum to be .010 inch.
(3) Insufficient control pump pressure.
Check the control pump pressure with a
gauge to be 160 Lbs , per sq. in. See
reasons for control pump pressure failure
in paragraph 93.
97. Ra i l grabs ope r a t e. - If the rail grabs operate
during a normal "Se r-vo ELect.r-Lc aL" controlled cycle, the trouble
will be in the setting of the rail grab controls and springs,
as the cams in the B-end are machined to prevent hoisting deceleration
and lowering acceleration rates in excess of 16 ft.
per sec. per sec. ,if the cams are properly adjusted. However,
if the rail grabs function when stopping or starting the car
in the middle of the cycle, the dashpot cylinder assembly is
improperly adjusted.
98. Slow starting of the hoist. - If the hoist requires
excessive time to start after the controls are set for !!Hoist-