SPEED REDUCERS–COMMONLY USED TERMS (part 2)
THRUST LOAD
The thrust load is the force imposed on a shaft parallel to the shaft axis. Thrust load is often encountered on shafts driving mixers, fans, blowers and similar pieces of equipment. When a thrust load acts on a speed reducer, the thrust load rating of the reducer must be high enough for the shafts and bearings to absorb the load.
MECHANICAL RATING
The mechanical rating is the maximum power or torque that a speed reducer can transmit, based on the strength and durability of its components. Obviously, the reducer may be rated no higher than the strength or durability of its weakest component. Reducers typically have a safety margin of two to three times their mechanical ratings. Thus, a reducer can withstand momentary overloads of 200-300% of its mechanical rating during a startup or other brief overload situation.
THERMAL RATING
The thermal rating is the maximum power or torque that a speed reducer can transmit continuously, based on its ability to dissipate heat generated by friction.
PRIME MOVER
The prime mover is the machine that provides power to a drive. The most frequently encountered prime movers include electric motors, internal combustion engines, hydraulic motors, and air motors. The type of prime mover used can affect the speed reducer during operation.
For example, an electric motor runs relatively smoothly in comparison to an internal combustion engine.
MOUNTING POSITION
The relationship of the input and output shaft relative to the floor line is called the mounting position.
INPUT HORSEPOWER
The amount of power applied to the input shaft of a reducer by the prime mover is input horsepower. It is often used as a basis for selecting power transmission components. Input horsepower appears in the rating tables or drive manufacturers' published data.
(Important: Input horsepower ratings represent the maximum amount of power that the reducer can handle safely.)
OUTPUT HORSEPOWER
The amount of power available at the output shaft of a reducer is the output horsepower. Due to losses caused by inefficiency, output horsepower is always less than input horsepower.
