PIV variable-speed drives are exclusively mechanical devices and characterized by a very high degree of precision in maintaining constant the set speed and by the power transmission of high output torque at a minimum speed.
The drives are divided into two main categories, i.e. the Standard A Series and GA Series of extreme accuracy.

PIV A Series variable-speed drives are essentially composed of two pairs of radially serrated conical wheels forming a pair of pulleys united by a rigid system of levers. The two pulleys are connected with each other by a special chain made of a group of blade packs in stainless steel. The constant input speed of the shaft is modified continuously on the output shaft through parallel and opposite axial movements of the disks forming both of the pulleys. The said movements force the chain to work on different, inverse and proportional diameters on each pulley. The chain is made of steel blades grouped in packs and enclosed in a cage, cages are united by pinions together forming the transmission belt. The blades in each pack, moving orthogonally in relation to the direction and movement of the chain, mesh into the slots of the serrated blades thus transmitting the power and the movement in a closed and precise mode.

In numerous industrial processes a small, yet very precise constant and reproducable modulation of speed ratio is required. In other words, a high setting accuracy and an absolute constancy in maintaining the set speed also in case of load variations.

In order to satisfy the said necessity, PIV has designed and carried out its PIV GA Series variable-speed drives which give a traditional mechanical drive of the A Series an epicyclic train set at input. The epicyclic train has the function of reducing the ratio of the basic drive, normally R=6, to values ranging between R=2 and R=1,005. It is to be noted that the extremely high accuracy in selecting and maintaining the speed in GA Series variable-speed drives is obtained exclusively through the system without an intervention of a control servomechanism.

GA series variable-speed drives also have an excellent weight-efficiency rate since only a small part of the power is transmitted through the chain.

PIV Variable-speed drives, A Series
Power rating: up to 9 kW
Variation Ratio: maximum 1:6
Input speed: n1=950 min-1
Precision: 3%
Lubrication: oil bath
Fields of Application:
textile industry, printing presses, paper machines, packaging industry

PIV Variable-speed drives, GA Series
Power rating: up to 31 kW
Variation Ratio: maximum 1:2
Input speed: n1=600 min -1
Accuracy : from a minimum of 5 up to a maximum of 0,5 ‰
Lubrication: oil bath
Fields of application:
printing presses, paper machines.