Intro to Sync Belts

1
Introduction to Synchronous Belts
2
Introduction to Synchronous Belts
Timing belts were invented in the late 1940s by
Richard Y. Case, an engineer with the former L.H.
Gilmer company, which was eventually absorbed
into Uniroyal Inc. The sewing machine provided
the impetus for the development of a belt capable
of synchronizing two or more shafts.
3
Introduction to Synchronous Belts
Applications required a very high modulus (no
stretch) tensile member to prevent distortion of
the pitch (the distance between the teeth) as it
rotated around the sprockets. Steel wire was
first used as a tensile member until later being
replaced by fiberglass and aramid fiber cords.
4
Introduction to Synchronous Belts
Synchronous drives represent a modern and
efficient system of power transmission. They
essentially combine the advantages of mechanical
components (gears chain) and flexible
components (flat V-belts) while eliminating
the inherent disadvantages of these components.
5
Basic Design Principles

• Synchronous belts operate on a basic principle
  molded teeth of the belt and mating grooves of
  the pulley make positive engagement. The teeth
  enter and leave the pulley in a smooth rolling
  manner with low friction. This positive
  engagement results in
• Exact shaft synchronization
• Elimination of slippage and speed loss common to
• v-belts.
• Synchronous operation at speeds higher than most
• chain drives.

6
Basic Design Principles

• All synchronous belts operate on the positive
  engagement principle. Chains operate on the same
  principle but synchronous belts have many
  superior characteristics. Synchronous belts wrap
  around the pulley by means of flexion and not by
  rotation of articulated parts (as chains do).
  This eliminates one of the causes of wear and
  noise.

7
Basic Design Principles
To maintain the correct tooth pitch as the belt
flexes around the pulley, the belt pitch line
(tensile cord) must coincide with the pitch
diameter of the pulley. The difference between
pulley O.D. and pulley pitch diameter is referred
to as Pitch Line Differential (PLD). For proper
tooth meshing the PLD of the belt must match the
PLD of the pulley.
8

When to Use a Synchronous Belt Drive

• Synchronous transmission between shafts is a must
• High mechanical drive efficiency and energy
  savings required
• Precise relative positioning of shafts (non-slip
  and minimal backlash)
• Compact drive layout is necessary
• Low maintenance is required
• Combines power transmission and conveying needs
• Low noise requirements (compared to chain)
• Environmental or contamination concerns (no
  lubrication required)
• High torque, low RPM requirements

9
Synchronous Belt Advantagesvs. chain

• Increased service life for belts and sprockets
• No need for lubrication
• - Improper lubrication of chain drives severely
  reduces life
• - Lubrication attracts dirt and leads to wear
• Reduction in noise over chain ( polyurethane
  drives)
• Environmentally cleaner no grease or oil
• Increased productivity less down time
• (vs. chain and v-belts)
• Increased efficiency and registration accuracy

10
Synchronous Belt Advantagesvs. chain

• Chain is heavier than belt systems
• Limited take-up or inaccessible drives - with
  synchronous
• belts, the required take-up allowances for
  tensioning are
• significantly less (v-belts and chain).
• No Hidden Costs chain cost of lubrication,
  disposal cost of
• lubrication, reservoirs
• Chain available only in full box lengths
• - (Typically 10 ft. in box)

11
Synchronous Belt Disadvantagesvs. chain

• Less initial cost (although synchronous payback
  is rapid
• due to reduced maintenance)
• Design Flexibility larger availability of
  ratios and
• lengths
• Less sensitivity to improper installation
• alignment and tensioning

12
Belt Construction
The main components of a synchronous belt are the
tensile cords, the teeth, rubber backing and
tooth facing.
tensile cords
rubber backing
tooth facing
teeth
13
Belt Construction

• Steel was originally used as a tensile cord
  material. Most belts today use high modulus
  (low-stretch) fiberglass or aramid fiber as the
  tensile member. (Kevlar is the Dupont trademark
  for an aramid fiber). Tensile cord is the load
  bearing element of the synchronous belt.
• The belt teeth are molded of a hard rubber
  compound jacketed with a tough, abrasion
  resistant nylon tooth facing. The compressive and
  shear strength of the teeth exceeds that of the
  tensile cords when there are at least six teeth
  in mesh with the driver pulley. Teeth in mesh is
  a critical design factor.
• A durable rubber backing encases the load bearing
  tensile cord. It protects the cords from dirt,
  oil and other contaminants, as well as frictional
  wear when a backside idler is used.

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Belt ConstructionS Z Twist
To reduce lateral movement, synchronous belts
are constructed by alternately spiraling S and
Z type cords. The synchronous belt cord is made
up of a number of small fiber strands twisted
together. These strands can be twisted either
clockwise or counterclockwise. The two twist
directions are referred to as S twist and Z
twist.
15
Belt ConstructionS Z Twist
Most synchronous belts are made with both S and
Z twist cord to minimize belt tracking forces
on the pulley flanges.
direction of belt rotation
16
Belt ConstructionZ Twist
When necessary, the lateral movement of a belt
can be pre-determined, if the direction of
rotation is constant (non-reversing drives). A
good example of this is Fin-Fan Drives. Because
the fin-fan drive has a vertical shaft, the belt
is built with Z twist construction only. This
gives the belt an upward direction of lateral
movement. This helps keep the belt off of the
bottom flanges and reduces excessive side belt
wear. Carlisle offers a special construction Z
twist construction for Fin-Fan air-cooled heat
exchanger drives.
17
Synchronous Drive Terms

• Unlike the V-belt drive, the synchronous belt
  drive is not a friction device. It is a positive
  engagement drive that is dependent upon the
  meshing of the belt teeth with the pulley
  grooves.
• The tooth profile indicates the type or shape of
  the belt teeth.
• The spacing between two adjacent teeth on the
  belt (and pulley) is referred to as the tooth
  pitch. The distance is measured from the center
  of one tooth to the center of the next.
• In synchronous belts, the belt length is
  determined by multiplying the belt pitch by the
  number of teeth in the belt. This is known as
  pitch length.
• In synchronous drive systems, backlash is the
  necessary clearance between belt teeth and pulley
  grooves for proper meshing.

18
Synchronous Drive Terms

• The pitch diameter of the pulley or (sprocket)
  refers to the diameter determined by the tensile
  cord location in the belt. Therefore, the pitch
  diameter of the pulley will be somewhat greater
  than the outside diameter of the pulley across
  the teeth.
• To maintain the correct tooth pitch as the belt
  flexes around the pulley, the belt pitch line
  (center of the tensile cord) must coincide with
  the pitch diameter of the pulley. The difference
  between pulley O.D. and pulley pitch diameter is
  referred to as pitch line differential (PLD).

19
Synchronous Drive Terms

• Tooth pitch is one indication of overall belt
  size. The larger the pitch, the larger the teeth
  and tensile cord. The larger and stronger the
  belt, the more horsepower it can transmit.
• In conventional trapezoidal tooth profile belts,
  letters indicate pitch, (MXL, XL, L, H, etc.)
  which are measured in inches.
• In curvilinear tooth profile belts, pitch is
  measured in millimeters (3M, 5M, 8M, etc).
• The terms synchronous belt and timing belt are
  used interchangeably.
• Sprocket and pulley are also used
  interchangeably.

20
Synchronous Belt Tooth Profiles

• There are two types of synchronous belt tooth
  profiles that make up the majority of synchronous
  drives in use today.
• Trapezoidal tooth profile (original
  technology) refers to the tooth configuration of
  MXL, XL, L, H, XH AND XXH type belts.
• Curvilinear tooth profiles have rounded tooth
  profiles that eliminate stress concentrations at
  the base of the tooth and allow more uniform
  stress distribution. Curvilinear profiles
  transmit high torque and represent the latest
  evolution of synchronous belt technology.
  Available in 3M, 5M, 8M, 14M, and 20M pitch.

21
Carlisle Tooth Profile Evolution

Trapezoidal Profile
A trapezoidal belt tooth has a constant angle of
pressure.
Original synchronous belt tooth profile
Curvilinear (RPP Profile)
The profile of curvilinear teeth has an angle
that increases from the base, to the top of the
tooth and allows for more uniform stress
distribution resulting in higher torque
transmission with reduced occurrence of tooth
jump.

Modern tooth profile
22
Trapezoidal Profiles
Trapezoidal profile belts are available in the
following pitches

• Pitch Pitch
• Designation Distance
• MXL 0.080
• XL 0.20
• L 0.375 (3/8)
• H 0.50 (1/2)
• XH 0.785 (7/8)
• XXH 1.25 (1-1/4)

23
Trapezoidal Pitch Sizes
MXL Mini Extra Light XL Extra Light L
Light Duty H Heavy duty XH Extra Heavy
Duty XXH Double Extra Heavy Duty
24
Trapezoidal Construction

• Fiberglass tensile member
• Synthetic rubber compound body
• Nylon tooth facing

25
Trapezoidal Features

• Fiberglass tensile member
• High breaking load, length stability (low
  stretch)
• Good resistance to repeated flexing
• Belt body synthetic rubber
• Good resistance to fatigue
• Resists heat, oil ozone
• Ground back for smooth operation low vibration
• Nylon tooth facing
• High resistance to abrasion
• Low coefficient of friction for smooth engagement
• Extended sprocket belt wear
• Low backlash
• Good for applications where high positional
  accuracy is required

26
Explanation of Part Numbers

• 300L100

100 1.0 Belt Width in hundredths of an inch
L 3/8 Tooth Pitch
300 10 30 inch pitch length Pitch Length
designated in tenths of an inch (hundredths of
an inch for MXL) example 440 MXL 025 440 100
4.4 inch pitch length
D300L100 dual sided
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Sycnhro-Cog Dual Timing Belt
Standard Lengths and Widths
belt belt belt pitch length type pitch
(inch) pitch (mm) range (inch) standard widths
(inch) DXL 0.20 (1/5) 5.080 15.0 33.0 .025 -
.037 DL 0.375 (3/8) 9.525 15.0 66 .050 - .075
1.0 DH 0.50 (1/2) 12.7 24.0 140.0 .075 1.0
1.5 2.0 3.0
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Curvilinear Tooth Profile
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Advantages of Curvilinear Profilevs.
Trapezoidal Profile

• Higher power ratings allow narrower widths to be
  used than trapezoidal timing belts
• More compact drives
• Lower overhung bearing loads (narrower widths)
• Quieter than comparable trapezoidal belts
• Covers wider range of power
• Reduced sprocket wear

30
Evolution of Curvilinear Tooth Profiles

• HTD - Curvilinear - Introduced by Gates in 1971
• STPD - Modified Curvilinear - Introduced by
  Goodyear
• in the early 1970s
• GT - Modified Curvilinear - Developed by Gates
  in the
• late 1970s
• RPP - Parabolic Dayco (Carlisle) introduced in
  the
• USA in 1985

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Curvilinear Profiles

• Curvilinear profile belts are available in the
  following pitches

• Pitch Pitch
• Designation Distance (mm)
• 3M 3
• 5M 5
• 8M 8
• 14M 14
• 20M 20

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Advantages of RPP Profile

• Interchangeable with existing deep groove
  profiles (HTD, HPPD, UPD)
• Sprocket availability - most major sprocket
  manufacturers provide RPP profile
• Sprockets use readily available QD bushing
• Quieter than competitive curvilinear belts
• RPP profile reduces sprocket wear

33
RPP Plus Synchronous Belt

• Highly energy efficient
• High Torque capability
• Provides up to 50 more horsepower capacity than
  first generation high-torque belts (HTD)

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RPP Plus
Precision Ground Neoprene Backing
Extra Strong Fiberglass Cords

• Tooth Indentation
• Shock Absorbing
• Reduces Noise

Patented nylon self-lubricating graphite loaded
tooth facing
Neoprene Rubber Belt Teeth
35
RPP Plus available in pitches of 3M, 5M, 8M,
14M, 20M
FEATURE
BENEFIT
Reinforced Parabolic Profile Wide range load
capacities speeds No lubrication High
mechanical efficiency Does not require friction
to operate
Positive slip-proof engagement No speed
variations Speed range more than double of
chain High torque capacity Wide range of
applications Clean, maintenance free Energy
savings Reduced overhung bearing loads Improved
motor life. Less heat build-up. Reduced
maintenance
3M is non-stock. Contact Carlisle for
availability.
36
RPP Plus available in pitches of 3M, 5M, 8M,
14M, 20M
FEATURE
BENEFIT
High torque capability Precision ground rubber
backing Fiberglass cord Nylon fabric tooth
cover
Compact drive package Lower cost Consistent
uniform thickness Reduced vibration Compatible
with backside idler Length stability High belt
strength High resistance to wear and shear Longer
belt life
3M is non-stock. Contact Carlisle for
availability.
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RPP Plus
Explanation of Part Numbers

• 800-8M-30

800 800 mm pitch length
8M 8mm pitch
30 30 mm width
38
RPP Plus
Standard Lengths and Widths
belt belt pitch length type pitch (mm) range
(mm) standard widths (mm) 3M 3 159 1263 6 9
- 15 5M 5 350 2525 9 15 25 8M 8 480
4400 20 30 50 85 14M 14 966 6860 40 55
85 115 170 20M 20 2000 6600 115 170
230 290 - 340
3M is non-stock. Contact Carlisle for
availability.
39

Dual RPP Plus

• - Used to drive shafts on (serpentine)
  multiple
• pulley drives in opposite directions
• - Available in RPP 8M 14M profiles
• - RPP molded teeth both sides - full power
  rating on both sides
• - Goodyear molded teeth one side Ground teeth
  on opposite side - 33 rating reduction on ground
  tooth side due to lack of fabric reinforcement on
  teeth

40
Dual RPP Plus
Standard Lengths and Widths
belt belt pitch length type pitch (mm) range
(mm) standard widths (mm) 8M 8 720 4400 20
30 50 85 14M 14 1400 4956 40 55 85
115 170
41
Dual RPP Plus
Explanation of Part Numbers

• D800-8M-30

800 800 mm pitch length
30 30 mm width
8M 8mm pitch
D Dual Sided
42
Introducing the New RPP Panther
The Panther Rules! The new RPP Panther with
ULTRA-CORD and Able compound provides fierce,
unequaled strength, efficiency and durability.
43
New RPP Panther with Able Compound
The Able Advantage
Reduces Tooth Shear
The new Able compound is reformulated for
increased performance. This advanced polymer
provides increased resistance to tooth shear and
tooth jump.
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New RPP Panther with Able Compound
The Able Advantage
Better Adhesion
Able adheres to the belt cords and nylon tooth
facing better than the old Panther compound.
This allows for reduced tooth deflection and
improves belt life.
45
New RPP Panther with Able Compound
The Able Advantage
More Robust
The Able compound is a robust material that
improves product consistency.
46
New RPP Panther with ULTRA-CORD!
The ULTRA-CORD Advantage
Reduced Tension Decay
Holds drive tension better than belts using
aramid fiber cords thus providing dimensional
stability for the life of the drive.
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New RPP Panther with ULTRA-CORD!
The ULTRA-CORD Advantage
Lower Installation Tensions
With ULTRA-CORD, there is no need to
over-compensate for aramid tension decay.
Lower tensions put less strain on drive
components such as bearings and shafts.
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New RPP Panther with ULTRA-CORD!
The ULTRA-CORD Advantage
Doesnt Absorb Moisture
The use of ULTRA-CORD eliminates the need for
special handling such as plastic bags and
desiccants used with aramid belts to prevent
shrinkage from moisture absorption.
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New RPP Panther with ULTRA-CORD!
The ULTRA-CORD Advantage

• Improved Flex Life
• Aramid tensile strength degrades over time with
  repeated flexing. ULTRA-CORD resists
  tensile degradation dramatically improves belt
  life and shock load resistance.

50
New RPP Panther with ULTRA-CORD!
The ULTRA-CORD Advantage
Improved HP Ratings

The new RPP Panther construction permits
increased drive horsepower ratings as much as 20
over the previous Panther.
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The New RPP Panther Some things didnt need to
be improved
SAME Great RPP Tooth Profile
The new RPP Panther still utilizes the same RPP
tooth profile for reduced noise levels,
resistance to tooth jumping, and improved meshing
with either RPP or HTD sprockets!
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The New RPP Panther Some things didnt need to
be improved...
SAME High Quality Fabric Facing
The New RPP Panther still utilizes the same
graphite- loaded, self-lubricating nylon fabric
facing for exceptional wear resistance, low
coefficient of friction, and superior drive
efficiency.
53
The New RPP Panther Some things didnt need to
be improved
SAME Industry Standard Sprockets
The New RPP Panther still operates with the same
readily available, industry standardized RPP
Panther sprocket systems.
54
The New RPP Panther Some things didnt need to
be improved
Still Works on Backside Idlers
The new RPP Panther is still the best choice (and
sometimes your only choice) for high torque drive
systems that require backside idlers.
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The New RPP Panther Synchronous Belt

• ULTRA-CORD
• Improves belt life
• Higher strength
• Reduced tension decay
• Dimensional stability

• Precision Ground Backing
• Smooth operation with backside idlers

• Able Compound
• Engineered polymer
• Increased performance
• Increased belt life

• Nylon Tooth Facing
• Graphite-loaded
• Self-lubricating
• Wear resistant

• Proven RPP Profile
• Greater transfer of power
• Jump shear resistant
• Reduced sprocket wear

• Tooth Indentation
• Shock absorbing
• Reduced noise

56
The Energy Efficient RPP Panther

• Panther improves energy efficiency
• - 98 operating efficiency
• Reduces energy consumption
• - As much as 5 over other PT systems

57
RPP Panther
Explanation of Part Numbers

• 3600-PTH8M-35

3600 3600 mm pitch length
PTH8M 8mm pitch
35 35 mm width
58
RPP Panther
Standard Lengths and Widths
Belt Belt Pitch Length
Type Pitch (mm) Range (mm) Standard Widths
(mm) 8M 8 480 4400 12 22 35
60 14M 14 966 4956 20 42 65 90 120
59
Panther Advantages over Poly-Chain

• Poly-Chain has a ribbed belt backing that does
  not work well with backside idlers.
• Poly-Chain is made of polyurethane and has a
  lower maximum operating temperature (185 F).
• Panther belts (rubber) have lower noise
  characteristics than (polyurethane) Poly-Chain
  belts.

60
NOISE COMPARISON
RPP Panther
Panther vs Competitive System
Test on belt pitch 8 mm / 20 mm wide, 2 pulleys
Z44, tension 46kg/strand
61
Energy Efficiency

• One third of the electric motors in the
  industrial and commercial sectors use belt drives
• Certain types of belts are more efficient than
  others, offering energy cost savings
• V-belts can have a peak efficiency of 95 to 98
  at the time of installation but deteriorates by
  as much as 5 over time
• Synchronous belts offer an efficiency of about
  98 and maintain that efficiency
• V-belts have a sharp reduction in efficiency at
  high torque due to slippage

62
Selling Energy Efficiency

• Conduct a survey of belt driven equipment in a
  plant or facility. Gather application and
  operating hour data. Then, determine the cost
  effectiveness of replacing existing v-belts
  with a synchronous system.
• Replace wrapped v-belts with Gold Ribbon Cog
  Belts where the retrofit of a synchronous belt
  drive is not cost effective.
• Consider synchronous belts for all new
  installations because the payback overcomes the
  price premium over v-belt drives.

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U.S. Customer Service 866-773-2926
Canada 866-797-2358
www.CarlisleBelts.com info_at_CarlisleBelts.com