Service manual

SYMPTOM: OUTPUT MOVEMENT IS ERRATIC AND VIBRATING
1. Input does not run at a constant velocity. The prime objective of a good input connection to an
Index Drive is to maintain a constant shock free velocity
(see input recommendations). Motor
running too slow could also cause an erratic output.
2. Output connections loose flexing, or winding up. Check all connections
(see recommended
output connections).
3. Excessive friction drag on output. Disconnect indexer and investigate friction torque.
4. Unit is overloaded due to excessive speed or loads. Contact our Sales people and check data
sheet application loads and speeds. Decrease speed.
5. Unit could be internally damaged. Check other symptoms.
6. Unit support is not ridgid. Check rigidity of index drive mount with an indicator. Stiffen support or
decrease speed.
RECOMMENDED INPUT CONFIGURATION
The prime objective of a good input connection to an Index Drive is to maintain a constant shock-free velocity.
Both the type of motor driving the indexer and the type of connection is of equal importance. Here we
explain some of the advantages and disadvantages of these factors.
1. Wormgear reducers with a high reduction provide two features. First, the flywheel energy due to
the high speed of the input. Secondly, the low efficiency of a wormgear reduces the effects of
backdriving and thus prevents input speed fluctuations.
2. Timing belts may be used if a wormgear drive is not suitable because of low gear reduction or
shaft arrangement requirements. Timing belts are desirable due to zero backlash and if properly
sized they have a long life. Timing belts also provide a flywheel effect of the pulleys and are ser-
vice free.
(Note: Use tapered bushings in all pulleys and use a high service factor). The pulleys
selected should be as large as possible to maximize the flywheel effect, and minimize belt flexing.
3. Zero backlash couplings are suitable, especially with tapered bushings. During installation, spec-
ial care is required to assure alignment of the couplings. When selecting a coupling a high ser-
vice factor must be used. Brands available are Thomas Coupling, Rexnord, Zurn Industries, etc.
Some customers have been successful with rigid couplings, but alignment of shaft becomes crit-
ical. Shaft failures are common in thses situations.
4. Gears and chains are not very desirable and should be used only if no other method is possible.
Gears should be set to minimum backlash and maximized in size. Unless enclosed and oil lubri
cated, only slow speeds are acceptable. Chains stretch and have backlash. A larger sprocket size
helps and some customers have been successful with self-adjusting idler arrangements.
5. Line shafting - Torsional windup is just as undesirable as backlash.
CAUTION: Long slender line shafts, rubber insert couplings, long belts and spongy mountings will
drastically increase actual torque demand which in turn again raises torsional windup. Breakage or
severe vibration can result.
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