Synchronous Installation

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Synchronous BeltInstallation and Tensioning

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Synchronous belt drives provide many maintenance
advantages that help in your daily struggle to
reduce equipment repairs and hold downtime to the
lowest possible level. Applying the practices
provided here will help to ensure that your
synchronous drives consistently give reliable
service and long life with minimal attention.
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Installation Check List
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Safety First

• Be sure to review and comply with all building
  and safety codes.
• Disconnect and lockout the power supply.
• Follow your plants safety rules!

5
Relieve Belt Tension
After removing the drive guard, loosen the drive
take-up and move the sprockets closer together to
facilitate the removal of the old belt and to
ensure installation of the new belt without
damage.
6
Inspect Drive Elements

• Inspect and replace faulty or damaged machine
  elements such as worn bearings or bent shafts
• This not only reduces the likelihood of future
  mechanical trouble, but ensures maximum service
  from the new belt

7
Clean Drive Elements

• Sprockets should be carefully cleaned of any
  rust and foreign material. A wire brush followed
  up with a shop cloth will usually do the job.
• This is a good time to service the take-up rails
  by removing any rust or dirt, and lubricating as
  necessary so tensioning of the new belt will go
  smoothly and easily.

8
Inspect Sprockets
Sprocket condition and alignment are vital to
belt life and performance. Never install new
belts without a thorough inspection of the
sprockets. Look for signs of wear such as bent
or missing flanges, worn or damaged sprocket
grooves, wobbling sprockets, cracked bushings,
etc.
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Inspect Sprockets

• The easiest way to check sprocket wear is with a
  Pi tape. The Pi Tape is graduated to the nearest
  0.001" and the sprocket can be measured by
  placing the tape around the OC of the sprocket.
  The Carlisle catalog provides the nominal
  sprocket OD. They are the same for RPP and HTD.
• OD tolerances for sprockets
• up to 50mm (1.969") 0.08/-0.00 mm
  (0.003/-0.000")
• 50 to 100 mm (1.969 to 3.937") 0.10/-0.00
  (0.004/-0.000")
• 100 to 175 mm (3.937 to 6.889") 0.13/-0.00
  (0.005/-0.000")
• 175 mm (6.889") 0.15/-0.00 mm (0.006/-0.000")

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Sprocket and Bushing Installation

• Improper sprocket and bushing installation can
  result in wobble as well as causing bushings or
  sprocket hubs to crack and possible shaft damage.
  When installing bushings such as QD or
  Taper-Lock types, always follow manufacturers
  instructions.
• It is important to never lubricate the tapered
  surfaces before installation. Friction is
  required to achieve the proper clamping force at
  recommended bolt torque. Lubrication causes
  excessive clamping force which usually results in
  cracking of the bushings at the bolt hole or
  keyway.
• Rust, grease and other debris on the shaft and
  mating surfaces can make installation difficult
  and affect torque carrying capacity. Clean these
  elements using a fine grit emery cloth and a
  clean rag.
• On flanged bushing types, the flange should never
  be brought up flush with the hub face. A small
  gap between the two surfaces is normal.
• When removing bushings, start at the jack-screw
  hole opposite the split to avoid cracking the
  bushing.

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Sprocket Installation Procedure
1. Thoroughly inspect the bore of the sprocket
and the tapered surface of the bushing. Any
paint, dirt, oil or grease must be
removed. 2. Assemble the bushing into the
sprocket. Loosely insert the capscrews into the
assembly, but do not lubricate capscrew threads.
(Note install M thru S bushings so the two extra
holes in the hub are located as far as possible
from the bushings sawcut). 3. With key in
keyseat of shaft, slide sprocket to its desired
position with capscrew heads to the outside. (A
few small sprockets may have to be installed with
the capscrews on the inside). If it is hard to
slide the bushing onto the shaft, wedge a
screwdriver blade into the sawcut to overcome the
tightness. 4. Line up the assembly so as not to
misalign the belts, and tighten capscrews evenly
and progressively. Apply the recommended torque
to the capscrews. There should be 1/8 to ¼gap
between the sprocket hub and the bushing flange.
If the gap is closed the shaft is seriously
undersize.
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Sprocket Safety

• Maximum Surface Speed
• Synchronous belt drives are designed to operate
  at sprocket surface speeds up to 6500 feet per
  minute (33 meters per second).
• Special sprockets are required for operation in
  excess of 6500 feet per minute.
• Where vibration is a critical factor, dynamic
  balancing of sprockets is recommended regardless
  of the operating speed.

WARNING Cast iron products can safely operate
up to a maximum speed of 6500 feet per minute.
For speeds greater than 6500 feet per minute
ductile iron must be used. Ductile iron has a
safe operating speed up to 10,000 feet per
minute.
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Preliminary Sprocket Alignment

• Use a straightedge or laser tool to make sure
  sprockets are aligned correctly
• A string can be used if a straightedge or laser
  tool is not available.
• Be sure the shafts of the driver and driven
  sprockets are parallel, horizontally and
  vertically.
• Be sure the driver and driven sprockets are in a
  straight line
• Be sure both sprockets are properly mounted and
  as near to the bearings as practical (to reduce
  overhung load on the bearings and shafts).

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Sprocket Alignment

• Proper Sprocket Alignment
• Synchronous belts are much more sensitive to
  misalignment than v-belts. Misalignment leads to
  uneven belt and pulley wear and premature tensile
  cord failure. Tracking problems can also result
  from drive misalignment.
• There are two types of misalignment, parallel and
  angular. In parallel misalignment, the driver and
  driven shafts are parallel, but the two pulleys
  lie in different planes. When the two shafts are
  not parallel, the drive is angularly misaligned.
  Any degree of pulley misalignment will result in
  some reduction of belt life. Total misalignment
  should be less than 1/16 misalignment per foot
  of drive center distance.

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Sprocket Alignment
The straight-edge should make contact at four
distinct points along the outside perimeter of
both sprockets.
1
2
There should be no gaps between the sprocket and
straightedge at 1-2-3-4
3
4
Proper Parallel Horizontal Vertical
(Off-Set) Angular Angular (Pigeon-Toed)
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Identify Replacement Belts
High torque synchronous belts (RPP Plus) are
similar in appearance to Super High Torque (RPP
Panther) belts. It is important to identify the
correct type of synchronous belt. To insure the
best performance and maximum belt life, replace
with the recommended belt.
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Installing New Belts

• Place the new belt on the sprockets. Loosening
  the drive take-up in advance makes this easy.
• DO NOT FORCE the belts on the sprockets by using
  a pry bar or rolling the sprockets.
• Do not crimp the belt.
• Move the sprockets apart until the belt is
  seated in the sprocket grooves, and start to
  tighten the drive just until the slack is taken
  up.

Prying or forcing synchronous belts onto the
sprockets can, and usually does, break some of
the load-carrying tensile cords. Crimping will
also damage the tensile cords.
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Apply Tension
The most important factor in the successful
operation of a synchronous belt drive is proper
tensioning. To achieve long trouble-free service,
belt tension must be sufficient to overcome tooth
jump and to insure proper meshing with the
sprocket. Improper tension is the most common
cause of premature belt failure.
Increase the center distance to apply
tension NOTE RPP Panther belts are constructed
to attain proper pitch dimension when subjected
to tension. For this reason, the belt may not
fully engage in large diameter sprockets without
applying tension to the belt.
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Tensioning Procedure
Method 1 Deflection Force Method A. Determine
the required deflection force range B. Calculate
or measure the free span length C. Determine the
deflection distance D. Measure the actual
deflection force E. Increase or decrease the
actual deflection force until it is within the
required deflection force range
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Recommended Tension Tables 8M Panther Ultracord
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Recommended Tension Tables 8M Panther Ultracord
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Recommended Tension Tables

14M Panther Ultracord
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Recommended Tension Tables 14M Panther Ultracord

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Spring Loaded Tensiometer Instructions
1) Measure the span length of the drive. Set the
large O-ring at 1/64 for each inch of belt span.
For example, set the large o-ring 1/4 for a
span length of 16, at ½ for a span length of
32, at 1 for a span length of 64 etc. 2) Set
the small O-ring at zero and press down the
tensiometer at the center of the belt span.
Depress the tensiometer until the large O-ring is
even with the bottom of a straight edge placed on
the outside rims of two sprockets. 3) Remove the
tensiometer and observe that the small O-ring has
moved from its original setting at zero to the
number of pounds required to deflect the belt to
the extent noted above.
Note For belts wider than 2 inches, it is
suggested that a rigid strip of keystock or
something similar be placed across the belt
between the point of force and the belt to
prevent belt distortion.
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Electronic Tensioning

• Method 2 - Frequency Method
• Another method to assure precise tensioning
  works on the principle of forced vibration
• The Frequency-Finder from Carlisle measures the
  frequency of vibration which is related to the
  tension of the belt

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Calculation of Belt Natural Frequency
T 0.0104 x K x L2 x F2

• Where
• T belt tension in pounds (Lbs)
• K mass of the belt span per inch (lbs/in)
• L length of vibrating span (in)
• f frequency of the belt vibration (Hz)

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Drive Engineer

• Tensioning information is also included in our
  drive design software for the deflection force
  and frequency methods
• Drive Engineer may be downloaded from
  www.CarlisleBelts.com
• or contact customer service [phone] to
  order CD

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Tensioning Notes

• Should jumping teeth occur, increase the belt
  tension until it ceases
• The supporting structure should be checked for
  rigidity to make sure the shafts are not
  deflecting during periods of peak loading and
  causing tooth jump
• Long center distance drives using relatively
  small diameter sprockets must provide sufficient
  tension to avoid the tension and slack sides of
  the belt from intermeshing

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Final Sprocket Alignment
Synchronous drives are highly sensitive to
misalignment. The closer you can come to perfect
alignment, the better. Proper alignment helps to
equalize the load across the entire belt width,
thereby reducing wear and extending belt life.
Laser alignment is the most precise method of
alignment and will aid in eliminating tracking
problems and belt and sprocket wear resulting
from drive misalignment.
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Start Drive
While the drive is running - look and listen for
any indications of potential problems such as
excessive drive noise, misalignment, sprocket
wobble, etc.
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Replace Guard
Ensure that the belt will not come into contact
with the guard. Often just replacing missing
bolts in the guard brackets will remedy this
situation.
NOTE Effective noise reduction for power
transmission drives can be accomplished by
incorporating a flexible noise absorbing material
with the protective guard. The guard design must
allow a cooling air passage on the top and bottom
to prevent overheating the drive.
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Re-Tension after 24 hours
When retensioning, it is necessary to use Ts min.
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Troubleshooting Synchronous Drives
Normal Failure Mode The end of the useful life of
a synchronous belt is most often
characterized by even tooth fabric wear and
eventually, tooth separation. Any other type of
belt failure could be an indication that there
are other problems present within the drive.
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Troubleshooting Synchronous Drives
Noise Noise can be an issue with synchronous belt
drives. The noise created by a drive increases
with the belt speed. To minimize noise make sure
the drive is aligned and tensioned properly.
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Troubleshooting Synchronous Drives
Sprocket Wear Sprocket wear can have a great
impact on belt wear. When unusual belt wear
occurs, the first step is to inspect the
sprockets. Excessive tooth wear is obvious with
visual inspection. Use a pi tape to evaluate
sprocket wear. The best sprocket material for
minimizing wear is gray cast or ductile iron. A
softer material may wear more quickly. Abrasive
environments, drive misalignment, and improper
tensioning can lead to rapid belt and sprocket
wear.
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Troubleshooting Synchronous Drives
Sprocket Misalignment The leading symptoms of
belt misalignment are excessive edge wear
(exposing or fraying the tensile cord), running
off the flange, snub breaking (in a stair step
pattern) and excessive drive noise. If sprockets
are verified to be in alignment and problems
persist, frame and bearing supports should be
checked for rigidity. The frame may be flexing
during operation, causing drive misalignment.
Proper Parallel Horizontal Vertical
(Off-Set) Angular Angular (Pigeon-Toed)
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Troubleshooting Synchronous Drives
Excessive Tension Excessive tension of a
synchronous drive will cause premature belt
failure due to wear and high tooth stress. The
noise level of a synchronous belt drive will
increase considerably if the belt is
over-tensioned. Excessive tension produces
fabric wear between the belt teeth exposing the
tensile cord and wearing of the sprocket teeth.
If tooth shear, snub break, or tooth jump occurs
under correct tension, the drive may be
under-designed.
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Troubleshooting Synchronous Drives
Under-Tensioning Under-tensioning is the most
common cause of belt failure. It can cause
premature belt wear, tooth jump and belt failure.
Belt wear is characterized by fabric wear on the
tooth flank which can accumulate material between
the teeth. Jumping can cause tooth shear and
tensile cord breakage. Tooth jump or ratcheting
occurs when the belt teeth climb up and out of
the sprocket grooves. The most obvious indication
of tooth jump is a machine gun like sound.
Although there may be no visible evidence of
damage, the capabilities of the belt are likely
destroyed after tooth jump.
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Troubleshooting Synchronous Drives
Non-Rigid Frame A less common cause of belt
failure is a non-rigid frame which allows the
center distance to vary when a load is applied.
The supporting structure should be checked for
rigidity to make sure the shafts are not
deflecting during periods of peak loading and
causing tooth jump.
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Troubleshooting Synchronous Drives
Overloaded Drive Severe overload conditions can
cause fabric and sprocket wear on the pressure
surfaces, belt tooth shear, snub break, tooth
jump and a resulting increase in noise level.
These conditions generally force a drive
re-design to provide additional capacity. A wider
belt will sometimes accomplish this.
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Troubleshooting Synchronous Drives

• Excessive Shock Loads / Start-Up Loads
• Some applications are not conducive to
  synchronous belt drives
• Use special consideration on drives with
  excessive or extreme shock loads or start-up
  loads - Some drives may require soft start
• Positive drive engagement and the high modulus
  cord (low-stretch) make synchronous belts less
  tolerant of severe shock loads than v-belts which
  allow slippage
• If you require the characteristics of
  synchronous belts in a shock load application,
  an RPP Panther synchronous belt is your best
  choice in these situations

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Troubleshooting Environmental Problems
Belt Deterioration The synchronous belt can
deteriorate when operated in caustic or acidic
atmospheres, environments saturated with vapors
from hydrocarbon solvents, and ambient
temperatures above 185F or less than -30F.
Specially constructed belts may provide
satisfactory service in a number of applications
not suitable for stock belts.
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Troubleshooting Environmental Problems
Excessive Heat Carlisle standard rubber
construction synchronous belts are compounded
for moderate resistance to heat and should give
adequate service life under normal conditions.
The operating limits of a standard construction
synchronous belt range from a minimum of -32F to
200F ambient temperature (230F intermittently).
Polyurethane synchronous belts are only capable
of 185F.
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Troubleshooting Environmental Problems

• Environments with Excessive Debris
• Synchronous belts should not be used in
  environments where excessive debris is present
• Debris can be more damaging to a synchronous
  belt drive than to a v-belt drive, which has a
  tendency to eject debris from the sheave grooves
  as the drive operates
• Large debris trapped between a synchronous belt
  and pulley will destroy belt tensile cords or
  drive hardware
• Small debris will become compacted in the pulley
  groove, forcing the belt to ride out away from
  the pulley and lead to belt failure by destroying
  the tensile member

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Troubleshooting Environmental Problems

• Environments with Excessive Debris (cont.)
• Exposure of synchronous belts to oil and other
  lubricants should be minimized
• Oil and petroleum distillates may alter the belt
  polymers and adhesion systems
• Care must be taken to provide adequate shielding
  on drives where debris or contaminants are likely
• Completely enclosing a synchronous belt drive
  may be acceptable. Synchronous belts generate
  less heat than v-belts. Air circulation around
  the drive is not a critical consideration except
  in extremely high temperature environments.

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Synchronous Belt Storage
The quality of a Carlisle Belt is not considered
to change significantly within eight years, when
stored properly under normal conditions. Normal
conditions can be defined as temperature below
85F and relative humidity of 70 or less with no
exposure to direct sunlight. Beyond eight years,
assuming normal storage, a decrease in service
life of approximately 10 per year can be
expected. For belts not stored under normal
conditions, the actual reduction in shelf life is
difficult to measure due to lack of precise data
and an infinite number of variables involved.
When belts are stored under abnormal conditions,
conservatism is recommended in estimating shelf
life. Improper or prolonged storage can reduce
service life considerably.
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Synchronous Belt Storage
Like V-belts, synchronous belts may be stored on
pins or saddles with precautions taken to avoid
distortion. However, belts of this type up to
approximately 120 inches are normally shipped in
a nested configuration and it is recommended
that the belts be stored in this manner as well.
Nests are formed by laying a belt on its side on
a flat surface and placing as many belts inside
the first belt as possible without undue force.
When the nests are tight and are stacked with
each rotated 180 from the one below, they may be
stacked without damage. Belts of this type over
approximately 120 inches may be rolled up and
tied for shipment. These rolls may be stacked for
easy storage. Care should be taken to avoid small
bend radii which could damage the belts.
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U.S. Customer Service 866-773-2926
Canada 866-797-2358
www.CarlisleBelts.com info_at_CarlisleBelts.com