Constant-fill, fixed-speed fluid couplings
Soft, no-load motor starting and adjustable starting torque at constant running speed — the dependable way to protect motors and driven machines from shock, overload and torsional vibration.
Three circuits, one purpose: torque tuned to your machine.
To satisfy the starting and running characteristics of industrial machines, Fluidomat offers three circuit types that bring starting torque down to as low as 120% of nominal torque. Type SM stands for shaft-mounted coupling; Type HF is the radially displaceable coupling.
- SM & HF (basic) — without delayfil chamber. Starting torque adjustable in the range of 180% to 275%.
- SMD & HFD (delayfil) — with delayfil chamber. Starting torque adjustable in the range of 150% to 275%.
- SM-DX & HF-DX (extended delayfil) — with extended delayfil chamber. Starting torque adjustable in the range of 120% to 270%.
Normal operating slip is just 2% to 5%, depending on coupling size and starting-torque value. A fusible plug blows off at 130°C as standard (optional 160°C) to protect the drive against sustained overload. Each coupling is suitable for two consecutive starts from hot and three from cold.

Key data
Why engineers specify constant-fill couplings
- Soft, no-load motor starting — the motor reaches full speed before picking up the driven load
- Built-in overload protection, with the fusible plug guarding against sustained stall conditions
- Absorption of shock loads and torsional vibration for longer gearbox and bearing life
- Lets rugged squirrel-cage motors replace costly slip-ring motors on hard-to-start drives
Choose your model
Each model is offered in basic, delayfil (D) and extended-delayfil (DX) executions to tune starting torque to your machine.
Steel-body couplings
Not sure which circuit your drive needs?
Send us your motor rating, machine type and starting-torque requirement and we’ll recommend the right constant-fill model and execution.