A urethane timing belt moves samples into position in this CAD simulation of an automated blood sampling machine. Timing-belt drives transmit torque and motion from a driving to a driven pulley or force to a linear actuator. They may also convey a load placed on the belt surface. A drive under load develops a difference in belt tension between the entering (tight) and leaving (slack) sides of the driver pulley. This effective tension, , is the force transmitted from the driver pulley to the belt and to the driven pulley or load: = tight and slackside tensions. The effective tension or working force generated at the driver pulley overcomes the driven pulley's resistance to motion. The driving torque, , is related to the driven torque (load), = pitch diameter of the driver pulley, = power required at the driven pulley, = angular speeds of the driver and driven pulleys of pitch diameters d , respectively, and = efficiency (typically about 0.94 to 0.96). A force equilibrium at the driver or driven pulley relates tight and slack-side tensions and the shaft reaction forces . In powertransmission drives, forces on both shafts are equal in magnitude: = belt wrap angle around the driver pulley. , is the tension set by an adjustable idler pulley. Pretension prevents belt slack-side sagging and ensures proper tooth meshing. In most cases, timing belts perform best when the magnitude of slackside tension is about 10 to 30% that of the effective tension. Although generally not recommended, belt drives can work without an adjustment mechanism. This is possible because, after initial tensioning and straightening, belts tend not to elongate or creep. Overall belt length remains constant during operation regardless of loading conditions, provided belt sag and some other minor influences are neglected. However, reaction forces vary under load. And
Products & Services
Timing Belts (metric)
Metric pitch timing belts mate with same-pitch timing pulleys in power transmission systems where maintenance-of-speed ratio is an important design consideration. Metric pitch is the distance between belt teeth based on millimeters (mm).
Timing Belts (inch)
English pitch timing belts mate with same-pitch timing pulleys in power transmission systems where maintenance of speed ratio is an important design consideration. English pitch is the distance between belt teeth based on inches (in).
Timing Pulleys (inch)
Timing pulleys mesh with same-pitch timing belts on synchronous drives where maintenance of speed ratio is important. These pulleys have an inch-based pitch designation.
Round Belt Pulleys
Round belt or grooved pulleys are used in drives and mechanical systems with o-rings or round belts, cables, ropes and wires.
Topics of Interest
Torque Transmission's 3/8" pitch timing belt pulleys ensures longer belt life with virtually no slippage and minimum backlash. A minimal amount of belt tension is required to prevent slippage,...
Our precision XL Series 1/5" pitch timing belt pulleys ensures longer belt life with virtually no slippage and minimum back lash. A minimal amount of belt tension is required to prevent slippage,...
Chapter 14: BELT DRIVES
Chapter 15: CHAIN DRIVES
Chapter 16: COUPLINGS
Chapter 17: SHAFTS
Wolfram Funk, Prof. Dr.-Ing.
Fachgebiet Maschinenelemente und...
The pretensioning of lightweight conveyor belts is critical to the long- term performance expectations of the customer. In the field I often get asked by my lightweight belting customers, how do I...
Timing belts and pulleys offer a positive drive through the engagement of molded teeth in the belt with accurately spaced grooves on the pulley. The action of belt teeth entering and leaving the...