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Gorman-Rupp Pumps 14A22-B 1064248 and up User Manual

Page 16

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10 SERIES

OM-00661

PAGE B - 9

INSTALLATION

parts can catch clothing, fingers, or
tools, causing severe injury to person­
nel.

V‐BELT TENSIONING

General Rules of Tensioning

For new v‐belts, check the tension after 5, 20 and
50 hours of operation and re‐tension as required
(see the following procedure for measuring belt
tension). Thereafter, check and re‐tension if re­
quired monthly or at 500 hour intervals, whichever
comes first.

Ideal v‐belt tension is the lowest tension at which
the belt will not slip under peak load conditions. Do
not over‐tension v‐belts. Over‐tensioning will short­
en both v‐belt and bearing life. Under‐tensioning
will cause belt slippage. Always keep belts free
from dirt, grease, oil and other foreign material
which may cause slippage.

Tension Measurement

Correct v‐belt tension can be achieved using a v‐
belt tension tester and Table 1 or 2. Use the tables
to find the v‐belt size (cross‐section), the smallest
sheave diameter, the belt type for your application.
The corresponding deflection force required for
new or used belts is shown opposite the RPM
range of the pump.

Belt Span

Deflection

Figure 5. Belt Tension Measurement

The ratio of deflection to belt span is 1:64 for both

ASA and metric units. Therefore, a belt with a span

of 64 inches would require a deflection of 1 inch at

the force shown on the Tables for your particular

application.

For example, if the span as measured in Figure 5 is

32 inches (813 mm), the v‐belt cross‐section is C,

the smallest sheave diameter is 8 inches, the pump

speed is 1250 RPM, and the belts are uncogged

Yy‐T type, then 11.5 lbs. of force on the tensioner

should show 1/2‐inch (12,7 mm) of deflection.

A tension tester is available as an option from Gor­

man‐Rupp (P/N 29513-001). Other tension test­

ers are available from your local belt/sheave dis­

tributor, and work on a similar principal.

To use the Gorman‐Rupp tensioner, measure the

belt span as shown in Figure 5. Position the bottom

of the large O‐ring on the span scale of the tension­

er at the measured belt span. Set the small O‐ring

on the deflection force scale to zero.

Place the tension tester squarely on the belt at the

center of the belt span. Apply force on the plunger,

perpendicular to the belt span, until the bottom of

the large O‐ring is even with the top of the next belt,

or with the bottom of a straight edge laid across the

sheaves.

Read the force applied from the bottom of the small

O‐ring on the deflection force scale. Compare this

force with the value shown in Table 1 or 2 and ad­

just the tension accordingly. Note that the tension

for new belts is higher than that for used belts to

allow for expected belt stretching. Do not over‐ten­

sion used belts to the higher deflection forces

shown for new belts.