Timing Belt
Home | Timing Belt

  Trapezoid Teeth
  T Type Teeth
  HTD, STS, RPP Type
  Double Sided Teeth
  Open Length










Timing belt drive consists of an endless belt whose inner surface has equally spaced teeth and belt pulley which have the relative teeth. It is a kind of new type drive which has synthesized all the good points of belt drive, chain drive and gear drive, while working, the teeth of the belt and the teeth of the pulley joggle each other to transmit the motion and the dynamic force.

Timing belt drive has such features as exact transmission ratio, non-sliding, constant velocity ratio which can be gained, smooth motion, absorption of vibration, little noise, the big range of transmission ratio which can normally reach 0.98, compacting structure, suitable to multi-axis transmission, no need lubrication, no pollution and so on. Therefore, the product can normally work well in the places where don't allow the pollution and where the working condition is bad, widely be used in machinery drives, such as textile, machine tool, tobacco, communication cable, printing, packaging, foodstuff, jet-express, sewing, electrical household appliance, petro-chemicals, sporting equipments, carving, etc.

Timing belts we produced have a lot of advantages: wear resistant, low elongation rate and high strength, resistant to wide temperature range, aging resistance, ozone resistant, etc.

Physical Mechanical Property of Industrial Timing Belts

Item Trapezoid Tooth Act Tooth
XL H XH XXH 3M 5M 8M 14M 20M
Tensile Strength (N/mm) 80 120 270 380 450 90 160 300 400 520
Elongation at reference load Reference load 60 90 220 300 360 70 130 240 320 410
Elongation (%) 4
Hardness (Shore A) 75±5
Adhesion strength of cloth 5 6.5 8 10 12 - 6 10 12 15
Adhesion strength of cord 200 300 600 800 1500 - 400 700 1200 1600
Gear shearing intensity 50 60 70 75 90 - 50 60 80 100


Timing Belts Design Data

The working condition coefficient KA        
Driven Pulley Drive Pulley
Ac motor (common torque squirrel cage type, synchronous motor), dc motor, multi-cylinder gas engine Dc motor (big torque, big slip, single-phase, slip ring), dc motor, single cylinder gas engine
Operating Time Operating Time
3-5 hours a day in intermittent use 8-10 hours a day in common use 16-24 hours a day in continuous use 3-5 hours a day in intermittent use 8-10 hours a day in common use 16-24 hours a day in continuous use
Copier, oil distributing device, testing instrument, film projector, medical appliance 1.0 1.2 1.4 1.2 1.4 1.6
Sweeper, sewing machine, office machine 1.2 1.4 1.6 1.4 1.6 1.8
Belt conveyor, light packer, oven, sifting machine, winding machine, conical shaper, woodworking-machine, band saw 1.3 1.5 1.7 1.5 1.7 1.9
Liquid mixer, powder mixer, drill press, lathe, thread producing machine, printing machine, planting machine 1.5 1.6 1.8 1.6 1.8 2.0
Liquid mixer, belt conveyor, boring lathe, grinding-machine, milling machine, gear pump, textile-machinery, centrifugal type compression pump 1.5 1.7 1.9 1.7 1.9 2.1
Elevator, spin-drier, cleaning machine, generator, exhaust fan, crane, exciting dynamo, sawmill, textile machinery 1.6 1.8 2.0 1.8 2.0 2.2
Centrifuge, flight conveyor, worm conveyor, hammering disintegrator, wood pulp processor 1.7 1.9 2.1 1.9 2.1 2.3
Clay mixer, mine using fan, blast blower, positive fan 1.8 2.0 2.2 2.0 2.2 2.4
Reciprocating compressor, ball mill, rod mill, piston pump 1.9 2.1 2.3 2.1 2.3 2.5
Note:  1 If it is gearing up please add the following factor into the KA:
  R=1~1.25 0
  R=1.25~1.74 0.1
  R=1.75~2.49 0.2
  R=2.5~3.49 0.3
  R3.5 0.4
2、 If the belt type is 14M or 20M and N1 600r/min, please add the following factor into the KA:
  N1 200r/min 0.3
  N1 201~400r/min 0.2
  N1 401~600r/min 0.1
If the transmission is like frequent positive and negative run or serious pound or emergent stop, please amend the factor according to the actual condition.

Design Procedure

Design Conditions:        
a. The type of the driver pulley and the driven pulley b. Daily working time
c. P: Nominal power P d. N1: Small pulley's rotating speed e. N2: Big pulley's rotating speed
f. Projected centre distance g. Special demand for the drive space    
Calculation Item Code Name Formula and Data Unit Information
Design Power Pd Pd=KaP KW The factor of working conditions, see Chart 1 Nominal power
The Type of Belt   According to n1 and Pd, choose from drawing 1, drawing 2, drawing 3, drawing 4   n1 the small pulley's rotating speed r/min
Drive Ratio i i=n1/n2   n2 the big pulley's rotating speed r/min
Pulley Diameter Pulley Teeth number Z1  Z2 Confirm it according to the principle of Z1 Zmin, it takes the round number after being calculated according to Z2=iZ1   Z1 is small pulley's teeth number, Zmin see chart 2
(mm) Pulley Pitch Diameter d1  d2 It has been calculated according to d1=Pb*Z1*3.1416 mm Pb is pitch, the small pulley's pitch diameter
  It has been calculated according to d2=Pb*Z2*3.1416 mm The big pulley's pitch diameter
Pitch Line Length Lp L0: projected length of the pitch line mm Projected centre distance, confirm it with the drive space
Choose Lp according to L0
Actual Center Distance a Approximate formula is: a= {M+[M²-8(d2-d1)2]½}/8 mm M=2Lp-(Z2+Z1)Pb
Gear Mashing Tooth Number Coefficient Kz Zm 6, Kz=1    Zm < 6, Kz=1-0.2 (6-Zm)   Zm is gear meshing tooth number
Zm=ent [Z1/2-PbZ1(Z2-Z1)/2aπ2]
The Fatcor of Width Kw Kw=(bs/bso)1/1.14    
Basic Rating Power P0 It recommends to use the basic rating mini width of various models. KW  
See Chart 3 ~ Chart 17 for P0
Rating Power Pr Pr=Kz*Kw*P0 KW  
Belt Width bs Confirm it according to the principle of Pd,  PdPr, bsbso(Pd/KzP0)1/1.14 mm Bso is datum width, see chart 18
Testing the Operational Capability Pr Pr=10-3v(kzkwTa-bsmV²/bs) KW Ta, m  see chart 19   V=PbZ1n1/60000
If Pr>Pd the design is good

Design summary: The type of belt, belt length, belt width
                                  The belt's code name
                                  The teeth number, pitch, diameter, width of the small or big pulley
                                  The type of pulley
                                  The pulley's code name
                                  The actual center distance