The KPTB is a variable fill fluid coupling designed to be a start up drive or variable speed drive.
The KPTB has an externally driven oil feeding pump and a remote electrically operated ON-OFF valve. When the valve is turned ON the fluid coupling circuit is fed, when it is turned OFF rapid oil drain occurs through orifices located on the periphery of the coupling. The forced bearing lubrication is continuously assured.
The oil pump flow can be operated through oil flow control valve or frequency converter (integrated into the oil feed pump motor), allowing KPTB to be a variable speed drive.
The KPTB range is suitable for powers up to 1700 kW as start up drive and 500 kW as variable speed drive.
The input and output straight shafts can be connected to electric motor and driven machine by elastic and flexible couplings.
Standard accessories include: oil motor pump, oil filter with pressure and temperature gauges, ON-OFF electric valve, oil temperature switch, oil level indicators, connecting wiring box with plug.
Optionals and include: water or air heat exchanger, quick release valves, output pulley, flexible and elastic couplings, cardan shafts and electric control board.

Special versions for low temperature operation and Eex design are available.


The variable fill fluid coupling allows a disconnect of the motor from the load granting the following advantages:

  • motor start up at no load
  • smooth start up even possible under nominal motor current by full starting control
  • shock and overload protection
  • absorbtion of vibrations
  • high radial load capacity (KPTE)
  • no belt slip
  • remote control by electric valve
  • load positioning
  • cheap and easy maintenance due to external mounting of main accessories like oil filter, feeding pump and control valve
  • longer life thanks to no friction linings to wear out
  • accurate variable speed performances


Start up drive:
– mills, crushers, wood chippers, grinders, shredders
– belt conveyors
– reciprocating and centrifugal pumps, compressors
– marine propulsion
– generators
– centrifuges, fans and blowers
– mixers

Variable speed drive:
– centrifugal pumps and compressors
– fans and blowers
– belt conveyors



The MPCB for KPTB and KSL, is an electronic device, designed and manufactured by Transfluid, with Transfluid’s proprietary software, capable of performing the following functions:

  • Monitoring of input and output fluid coupling speed
  • Monitoring of all fluid coupling parameters
  • Sending fc status and alarm signals to the main control room
  • Implementation of interlock logics
  • Local or remote output speed control



A part of a conveyor system to transport coal to the central power plant.
The system foresees several fluid couplings; even for double drive systems.
To make the system more compact and easier to install, the feeder pump, heat exchanger and lubrification pump were all installed on the KPT.
For this application the electrical cabinet for soft starting and controlling the torque was installed.

13 KPT

A multistage pump for a snow cannon.
The coupling EKPT was designed to be mounted on a 2 pole electric motor. It is directly mounted to the B5/B3 flange.
The result is a solution very compact and simple where the coupling is used as a speed controller (typical ratio of 4:1)

15 KPT

Multistage pump for snow cannons.
The coupling KPT in version shaft-to-shaft has been designed for 2 and 4 pole electric motors.
The connections between the electric motor and the driver equipment has been made through tooth couplings in this application.
The group is used as a speed controller (typical ratio of 4:1).
The performance, sturdiness, reliability, simplicity in maintenance and a long life makes the KPT ideal for difficult applications.

21 KPT

A system for the operation of a grinder in cement block fabrication.

24 KPT

Speed controller of a centrifugal pump for a furnace. KPTs can be used to vary the velocity of pumps and fans.
In this application a KPT was chosen instead of an inverter eliminating EMI, and allowing the electric motor to be powered directly. The maintenance can be performed without highly specialized personnel.
The fluid coupling allows a variation of speed with soft transients, absorbtion of torque spikes and the dissipation of overloads giving the drive train a longer life and reducing operating costs.
This KPT coupling is used as a speed controller for powers up to 500 kW.
Above 500 kW Transfluid has available the model KSL.
Transfluid has been able to increase its knowledge base through applications in different sectors allowing a wider range of experience to give to our clients.
The range of accessories applicable to the KPT series include:

  • pressure switch
  • temperature switch
  • oil level indicators
  • heat exchangers:
    air to oil
    water to oil
  • quick drain valves
  • variable fills
  • flanged for cardan shafts
  • pulleys
  • electric cabinets and controls

To allow quick installations and commissioning it is possible to supply a complete group with controls on the equipment or wired for remote.

29 KPT

Power of a hammer mill for a metal grinder.

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