F-Type Primary Speed Reducer
DBS Manufacturing, Inc. pioneered the concept of using hydraulics as the means of primary speed reduction on clarifier and thickener drive units. DBS incorporated the hydraulic speed reducer on its drive units in the early 1990s and it is now a standard feature on nearly all DBS drives.
DBS hydraulic primary speed reducers, or F-type speed reducers, are truly "State of the Art." These primary speed reducers incorporate a hydraulic pump and motor fully enclosed in a reservoir for clean operation. F-type primary speed reducers perform several important functions:
Speed reduction: Many reduction ratios are available.
Torque limiting: Maximum torque cannot be exceeded. Once maximum torque is reached, the drive will slow down but still maintain torque. This is analogous to a truck shifting into lower gears when pulling a load up a hill.
Low maintenance: Change oil filter every three months.
Long life: Hydraulic components have been proven to last for years in continuous duty industrial clarifier and thickener applications.
Easy repair: All components can be removed with common hand tools. No special skills or training is required to maintain the unit. Most items can be replaced with alternate brands.
Reversibility: An optional directional control valve can provide easy reversing to allow clarifier or thickener rakes to be backed out of an overload condition. Torque overload protection is maintained when operating in reverse.
The main features of the F-type primary speed reducer are its reliability and its ability to operate at high torque in or near a stall mode. In a high-load, over-torque situation, the F-type primary speed reducer will keep the clarifier or thickener operating if at all possible. If the rakes are truly stuck, the F-type primary speed reducer will simply stall at a high, but safe, torque.
The operation of the F-type primary speed reducer is simple. The electric motor drives a hydraulic pump that delivers oil to a hydraulic motor. The hydraulic motor drives the output drive shaft of the F-type primary speed reducer. The displacement of the pump is much smaller than the displacement of the motor. This difference in displacement between hydraulic pump and motor results in speed reduction. A pressure relief valve provides torque-limiting protection.
Since the system pressure is directly proportional to the torque load, the torque gauge and switches operate by monitoring the system pressure. This provides an accurate torque reading and a pressure signal that can be used to drive a 4-20 mA torque transducer.