Drum motors in general

A drum motor is an electric motor drive enclosed within a shell designed to drive conveyor belts or many other applications.

Solid maintenance-free design

The drum motor takes up little installation space as the electric motor, gearbox and bearings are placed inside the drum. In order to keep moisture and dirt out of the motor, the whole system is sealed with high-quality components, adapted to the various conditions in which the drum motor performs. Both the gearbox and motor are oil bath lubricated for lubrication and heat dissipation. As a standard the shell is crowned to guarantee the tracking of the conveyor belt.

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Long service life

All our gears are made of high alloyed, case hardened steel. In the finishing process the sprockets are ground or honed for high quality, low noise and long service life.

The ball and needle bearings have generous dimensions. Power is supplied directly to the stator (standard insulation class F). As only three-phase motors are used, collector rings or brushes are not required.

Easy maintenance

The drum shells are securely bolted to the shell for easy disassembly.

The drum motors are fitted as standard with terminal boxes which allow maximum rotations of 180° clockwise and counter-clockwise for cable entry.

Further versions and standards

All motors are made according to protection class IP66 as standard. The speed of a GV drum motor can be controlled by means of a frequency converter. If necessary, a backstop or electromechanical brake can be installed. On request drum motors can be supplied according to CSA C US or UL regulations. Motors are available in full or partial stainless steel design (304 or 316). All motors have a CE mark. Special seals for extreme conditions can be provided.

Tail pulleys and fixings

Van der Graaf has the right tail pulley and shaft sleeve for every drum motor.

An overview of the unique qualities of Van der Graaf drum motors

 

Oil seals on hardened stainless steel raceways

Drum motor shafts are generally made of steel. Seals rotating directly on the shaft may cause running marks on the shaft, which may lead to cause oil leakage over time. Van der Graaf’s hardened and ground stainless steel outer rims as the raceway for the retaining rings will prevent these leakages.

Oil change after 25,000 operating hours

Van der Graaf knows there is always little concern and time for oil changes: our drum motors require oil changes after 25,000 hours of operation.

Rotatable terminal box

It is not always possible to install a drum motor in such a way to have the power cable directly under the cable gland in the terminal box. If cables are laid in a loop, they will increases the risk of damage. Another option is to completely disassemble the terminal box and reassemble it in the correct position. Van der Graaf has solved this problem; by loosening an Allen bolt the terminal box can be rotated 180°, allowing for easy mounting in the correct position.

Shells in cast iron or stainless steel

Other drum motors often have aluminium parts. Van der Graaf uses only cast iron, for the shields as well as the stator housing, motor shield, gear housing and of course the terminal box. When subjected to external impacts or high tyre pressure, aluminium cannot compete with the strength of traditional raw materials.

Flattened trunnions

Van der Graaf offers double security: all our standard trunnions are flattened. If you construct your mounting brackets correctly (or use our shaft sleeves), you will achieve optimum protection against twisting. Why not opt for this security even during normal conditions?

Removable drum shells

Almost all drum motors, especially 80 to 320 millimetre motors, are nowadays equipped with pressed-on or glued drum shells. Although this makes the motor cheaper, it will affect the serviceability that industrial products require. The removal of a drum shell in this case is difficult, and can only be carried out with special tools or through a process in which the drum motor is heated, but this may burn the lagging. In practice, saving on design and assembly will increase the cost of maintenance. For this reason, Van der Graaf drum motors have drum shells screwed onto the motor, one for the smaller ones and both for the larger ones. Your maintenance service will benefit greatly from this method of assembly.

Honed and ground gear flanks

The noise level of drum motors depends first of all on the quality of the gears and rings. Van der Graaf does more than just milling or hard milling when producing these parts. Grinding and honing the gear flanks is a standard procedure in order to produce the highest possible quality of gear.

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Insulation class

Our drum motors are fitted as standard with windings of insulation class F. This means that the temperature of the winding may not exceed 155 degrees Celsius.

Type plates made of stainless steel

Type plates must not get lost, rust away or become illegible. All Van der Graaf type plates are stainless steel and attached to the drum shell with rivets. On stainless steel shells all data are lasered, so that it is not likely that any data on our motors will get lost.

Applications

Van der Graaf drum motors can be found all over the world in various industries. Sectors that frequently use our motors are the agricultural sector, transport, fishing and mining industries. Please find our picture page for pictures of the versatile applications of our products. If you are in doubt whether a drum motor is suitable for your application, please contact us.

Specials

We often get questions about whether our drum motors can be used for a specific purpose. Together with our Engineering Department, customers usually find a suitable solution. Some examples of special applications will give an impression of what our company can achieve.

RVS trommelmotor

This drum motor, made entirely of stainless steel, has a profiled shell for driving a modular belt.

This ice breaker is made entirely of stainless steel and fitted with eighteen blades. This drum motor rotates in an installation to chop up large slices of ice with fruit.