Variable Speed Drives
Variable Speed DrivesBerges Antriebstechnik GmbH & Co.KG (Germany)
BERGES is one of the world's leading suppliers of mechanical infinitely variable pulley systems.
Their extensive range of ready-to-install components covers a power range of 0.25 up to 200 kW.
For many applications, mechanical pulley technology is the easiest and most solid alternative to sensitive electronics.
Normal or wide V-belt technology, single- or double pulley drives, spring or cam pulleys, ready-to-fit RGAE assembly units, supplementable with 3-phase A.C. motors and reduction gear boxes, for nearly every application the right solution is already available in BERGES's standard range.
Double pulley type RFb and RDb for wide belts up to 160 kW motor power. Double pulley drives type KRM, RF for standard belts.
Single pulley type Fsb for wide belts up to 55 kW motor power. Single pulley drives type KM, Fs for standard belts.
Symmetrical pulley technology up to 160 kW
- Consistent contact pressure on the flanks
- Wedge-shaped symmetrical cross section
- High power transmission at low masses
Double pulley drive RF b for wide V-belts
A mechanical variable pulley Rb. mounted on the driving shaft (motor shaft) and a spring-loaded variable pulley Fb, mounted on the driven shaft* form a variable pulley set with fixed centre distance RF b. Also suitable for reversing operation.
Double pulley drive RD b for wide V-belts
This pulley set has a torque-dependent control cam in addition to the pressure springs to absorb intermittent overloading or torque peaks.
Double pulley drive KRM, RF for standard V-belts
These pulley sets are designed for use with standard V-belts in special applications. The KRM type pulleys are designed as plain pulleys and RF types with interlacing pulley sheaves.
Speed adjustment controls for double pulley drives
The variable pulley and control device are mounted together centrally on the drive shaft. This arrangement has the advantage that there are no additional axial loads on the motor shaft bearing.
Single pulley drives Fsb for wide V-belts
In this system, a spring pulley which opens on both sides (Fsb) is used in conjunction with a fixed driven pulley. Speed adjustment takes place by adjusting the center distance by way of the motor carriage or tilting base.
Single pulley drives KM, Fs for standard V-belts
This single pulley drive for normal V-belts is assigned to a fixed counter pulley. The spring-loaded pulley is designed either to open on one side (KM) with a flat sheave or to open on both sides (Fs) with comb-shaped sheaves. The speed can be adjusted by changing the centre distance using a motor slide or a rocker.
Asymmetrically variable speed pulleys up to 200 kW
- Asymmetrical cross section
- High power transmission up to 200kW
- Reduced heat development
- Asymmetrical V-belts have a lower belt volume and thus for higher lateral rigidity and less heating, resulting in higher load capacity and longer service life
- Asymmetric output pulleys are also available with torque-dependent pressure cams, which automatically and permanently guarantees the optimum axial pressure of the V-belt and thus prevents belt slippage during peak- and overload operation or machine starts.
As the only manufacturer worldwide, Berges can offer both symmetrical and asymmetrical pulley drive technology. Asymmetrical control-cam pulleys on the output side are equipped with a torque-dependent pressure device, which automatically and permanently ensures the optimal axial pressure of the V-belt. This prevents the belt from slippage in shock and overload operation or when starting the machine and protects the belt in normal operation to enhance its durability at the same time.
Single pulley drives FG
Asymmetrical drive units FG for 0,75 – 45 kW motor ratings, comprising:
- Spring-loaded regulating pulley F mounted on the motor shaft
- Fixed-diameter driven pulley mounted on the machine or gear shaft.
The axial pressure on the V-belts is exerted by compression springs with optimally dimensioned characteristics. Speed variation is achieved by changing the centre-to-centre distance by means of a sliding motor base plate. Speed variation within ratio of 1 : 3. This system provides a high torque at a low output speed.
Single pulley drives GF
Asymmetrical drive units FG for 1,1 – 45 kW motor ratings, comprising:
- Fixed-diameter driven pulley mounted on the motor shaft
- Spring-loaded regulating pulley F mounted on the machine or gear shaft
The axial pressure on the V-belts is exerted by compression springs with optimally dimensioned characteristics. Speed variation is achieved by changing the centre-to-centre distance by means of a sliding motor base plate. Speed variation within ratio of 1 : 3. This system provides an almost constant output power over the entire control range.
Double pulley drive RF, RFN
Asymmetrical drive units RF, RFN for 0,37 – 45 kW motor ratings, comprising:
- Mechanically adjustable regulating pulley R with integral central adjustment
- a) Spring-loaded regulating pulley F
b) Type FN with increased diameter for lower output speeds
The axial pressure on the V-belt is achieved by compression springs. This drive system is characterised by high dynamics when the rotational speed changes. It can be used for reverse operation as well.
Double pulley drive RK, RKN
Asymmetrical drive units RK, RKN for 4 – 150 kW motor ratings, comprising:
- Mechanically adjustable regulating pulley R with integral central adjustment
- a) Output pulley K with automatic torque-dependent pressure device
b) Type KN with increased pulley diameter for lower output speeds
This drive system features a high level of efficiency even in the partial load range. The system is suitable for high starting torques and offers excellent overload safety.
Assembly units RGAE
A BERGES RGAE consists of a housing, pulleys and a wide V-belt and can be complemented by a gearbox flange / gearbox foot.
On the output side, the Assembly Unit RGAE can be equipped with foot or flange bearings and a double-bearing shaft (gearbox flange) for connecting any drive element, as well as direct mounting of reduction gears with IEC connection dimensions.
We can deliver the Assembly Units RGAE with a speed control, motors and reduction gears as one complete unit.
Assembly Unit RGAE
A BERGES RGAE consists of a housing, pulleys and a wide V-belt. It can be complemented by a gearbox flange / gearbox foot.
Gearbox flange GFL
Flange bearings, shaft (gearbox flange) is supported by a double bearing, are used to connect any drive element such as chain and belt drives and also for the direct mounting of reduction gears with IEC connection dimensions.
Gearbox foot GTF
To complement our gearbox flanges an individual gearbox foot is available in every size.
Speed Control Devices for Assembly Units RGAE
Just carry out the stepless speed control yourself: mechanically by handwheel or by remote setting.
Variable speed units
Any combination of gear type and motor design is possible. Please contact us. We will provide the perfect solution for you.
We would like to draw your attention to our free service/consultation when replacing stepless-variable V-belt drives from other manufacturers.
ATEX variable speed units
BERGES variable speed units are explosion-proof according to directive 2014/34/EU and are classified for equipment group II of category 2 and 3 – EX II 2 G h IIB T4 Gb and EX II 2 D h IIIC 135°C Db. They are available with a reducing gear box or gearbox flange optionally.
These ATEX units are especially suitable in mining applications where an explosive atmosphere of gases, vapours or dust can occur.