Thrush 3500 RPM - Manual (Page 3)

ALIGNMENT
The pump and driver were accurately aligned at the factory. However, it is impossible to maintain
this alignment during shipping and handling. Therefore, it will be necessary to realign the pump
and driver. Flexible couplings are not universal joints and should not be used to compensate for
misalignment of the pump and motor shafts. Their function is to transmit power from the driver to
the pump while compensating for thermal expansion and shaft end movement. The coupling
faces should be far enough apart so that they do not make contact when the motor shaft is forced
to the limit of the bearing clearance toward the pump.
There are two types of misalignment encountered with flexible couplings: ANGULAR
MISALIGNMENT in which the shafts are not parallel and PARALLEL MISALIGNMENT where the
shafts are parallel but not on the same axis.
STRAIGHT EDGE ALIGNMENT
All THRUSH base mounted end suction pumps are furnished with flexible couplings. To check
alignment, simply place the alignment gauge furnished with the pump across the coupling
flanges, making sure the edge is firmly against the coupling halves. If parallel misalignment
exists, there will be a gap under the gauge. To correct this, loosen the motor, hold down bolts
and realign or shim motor until the alignment gauge rests firmly on both coupling halves as in
Figure 2. Check alignment at 90° increments around the circumference of the coupling. (Do not
rotate shaft for this check.) If alignment is correct, retighten motor bolts. After the bolts have
been tightened, recheck alignment. Angular misalignment can be checked with a caliper by
checking the spacing between coupling halves at 90° intervals. If misalignment exists, realign as
previously described.
DIAL INDICATOR ALIGNMENT
To check angular alignment with a dial indicator, remove coupling insert, clamp the dial indicator
to the pump coupling half so that the ball on the indicator just rests on the face of the motor
coupling half. A chalk mark should be made at the point where the ball contacts the coupling half.
Both the pump shaft and the motor shaft should be rotated an equal amount so that the reading is
taken at all check points with the ball on the chalk mark. Insert shims as required. To check
parallel alignment with the dial indicator, the ball should rest on periphery of the motor coupling
half. A chalk mark should be made at the point of contact, and the shafts rotated equally so that
the reading is taken with the ball on the chalk mark at all check points. Insert shims as required.
NOTE: ANY ADJUSTMENT TO CORRECT ONE DIRECTION OF ALIGNMENT MAY AFFECT
THE OTHER DIRECTION. THEREFORE, IT IS NECESSARY TO RECHECK BOTH ANGUALR
AND PARALLEL ALIGNMENT AFTER EACH ADJUSTMENT.
THRUSH STANDARD COUPLINGS (TB WOODS) WILL OPERATE SATISFACTORILY WITH
1/16” PARALLEL MISALIGNMENT OR 1 Deg. ANGULAR MISALIGNMENT MAXIMUM. ON
OTHER COUPLINGS CONSULT MANUFACTURE’S DATA.
Figure 2