The two -drum drive is most often located along the lower branch of the tape at a certain distance from the end unloading drum, which provides the best conditions for its operation.
Most of the cargo remaining on the tape after unloading manages to fall on the way from the end drum to the first drive. The load remaining on the tape sticks to the first drum and can slightly increase its diameter. As a result, the speed of the tape on this drum increases slightly and on the site between both drive drums the tape weakens, which does not create any difficulties in operating the drive.
In the two -drum drive, the reverse side of the tape wrapps the second drum immediately after bypassing the head unloading drum. Sticking on this drum increases significantly and leads to the reassignment of the tape. Such drives should be avoided. In the case of the use of such a drive, each drum is rotated with a separate engine or use a differential, avoiding a rigid connection between drums.
The greatest clutch force can be created by a clamping ribbon, a cladding drive drum outside or from the inside of the main tape. The clamping tape is an endless ring pulled by screws, springs or loads.
The outer tape grabs the drive drum from the outside and creates an additional pressing of the main tape to the drum. The inner tape is, as it were, a continuously moving lining of one drum; On another drum, she, just like the external, presses the main tape.
It is recommended to use a thin clooper tape as a clamping. Such drives have a large clutch and can push the tape, t. e. pull its running branch with zero tension of the escaping
The drives with a clamping ribbon did not gain widespread. The manufacture of a clamping tape is difficult, since for reliable operation of the drive it must be ring with strictly parallel edges. Great difficulties are caused by adjustment of the stroke of the clamping tape; With inaccurate installation of drums or accidental hitting particles of cargo between ribbons or between the tape and the drum, it goes to the side.