Flat belts

A flat belt often consists of various layers which are connected via intermediary layers.

The upper side and underside are referred to as top layers and can consist of the following materials:

• Chrome leather (L)
• Elastomer (G)
• Polyurethane (U)
• Tissue (T)
• Polyester fibre fleece (N)
• High Grip / Medium Grip ®

The medium layer is the tension member that consists of:

• Polyester fabric
• Polyester cord
• Aramid cord
• Polyamide fabric
• Polyamide strip
• Polyurethane film

To get a better understanding of these belt drives, it is important to know, that the outer area can only realize a limited power transmission with one cord.

The power is transmitted with frictional locking between belt and pulley. With the different surfaces the belt can be adjusted perfectly to the surroundings. Chrome leather for example is suitable for belt pulleys with an oil and water layer as the leather absorbs the humidity retrieving the friction value.

Also with generator drives chrome leather is a popular solution to reduce the so-called “stick-slip-effect“, which usually causes performance fluctuations on the generator.

Why does the flat belt stay on the pulley and does not run off?

Flat belt pulleys are carried out crowned according to DIN 111 or ISO 22. At least one pulley in the drive should be crowned.

Due to the curvature of the pulley, there are different circumferential speeds on the pulley. The fastest circumferential speed is on the curvature vertex.

Each point on the belt´s cross section tries to reach the fastest circumferential speed. Thus the belt centres around the centre of the pulley.