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After about one week of operation, new V-belts will
have stretched somewhat. The motor must be moved
on its slide base to re-establish proper belt tensioning.
Insufficient tension results in slippage, burning,
squealing (especially during starting) and shortened
belt life. Overtightening imposes excessive loads on
pump and motor bearings and can cause early shaft
fatigue failure.
Use the following table in adjusting V-belt tension:
Belt Tension at Mid-Span
Cross-Section New Belts Used Belts
“B” 5 – 6 lb. 3-1/4 – 5 lb.
“C” 9-3/4 – 13 lb. 6-1/2 – 9-3/4 lb.
“3V” 4 – 10 lb. 3 – 7-1/2 lb.
“5V” 17 – 30 lb. 13 – 23 lb.
Applying the above forces with a small spring scale,
adjust motor position to provide the following deflection
at mid-span:
Approx. Center Distance
(Span), inches
Deflection,
inches
16 1/4
22 3/8
28 7/16
32 1/2
40 5/8
48 3/4
60 15/16
Belts must be matched in pitch length. If one or
two belts are slack, when the others are correctly
tensioned, investigate for possible reasons. Correct
any misalignment or lack of matching so each belt will
transmit its load share.
Sheaves must be balanced to prevent abnormal
vibration. Balancing weights must NOT be removed.
Type “QD” sheaves must be evenly tightened on their
tapered hubs to avoid rim wobble and severe lateral
vibration. V-belts that snap and jerk will produce
abnormal vibration and loads on both pump and motor
or engine.
Run the pump several minutes at full load with belt
guard re moved, observing for uneven motion on the
belt slack side, espe cially.
When an old V-belt drive becomes unserviceable,
replace ALL belts, not just the broken or cracked belts.
Do not operate belts on sheaves having worn, rusted,
greasy or broken grooves. Shut off power to driver
before servicing drive or pump.
WARNING: Do not operate without appropriate guards
in place.
DIRECTION OF ROTATION
Before placing pump in operation, check that
crankshaft rotation agrees with the arrows cast on top
of the power frame by briefly jogging the electric motor.
Crankshaft rotation must be clockwise as viewed from
the right side of pump.
If pump is gear driven, remember that the pinion
shaft turns opposite the crankshaft, if using a single-
reduction geared drive or in the same direction as the
crankshaft when using a planetary gear.
AUTOMATIC (SAFETY) SHUTDOWNS
Carefully check all electric shutdown devices present,
such as crankcase oil level, discharge pressure,
vibration, lubricator oil level, motor thermostat, etc.
CRANKSHAFT ASSEMBLY
GENERAL
Myers Aplex Series crankshaft suspension uses two
single-row tapered bearings, which are shim adjusted
to provide the correct running clearance.
Thorough cleaning of all components prior to assembly
is essential.
Power frame, shaft, bearings and retainer MUST be
scrupulously scrubbed with clean solvent (such as
kerosene) before starting. Remove any oil, dirt, rust and
foreign matter which might prevent the correct fit up.
Crankshaft journals are critical. Remove all burrs, rust
spots, and nicks, paying special attention to the ground
areas on which bearings and oil seals operate.
TAPERED ROLLER BEARINGS
Shaft and frame tolerances provide a tight (shrink) fit
on the shaft and in the carrier. The best way to install
the cone assembly (consists of the inner race, cage
C.D.
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