Rotary Power Transmission

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4. Consider other characteristics of the system components

As well as the more visible characteristics such as dimensions, location and orientation there are those factors which result from a relationship between input and output. These will not be defined by the manufacturer but will be derived characteristics. For instance, if a gearbox is used to provide a torque amplification then the difference between the input and output torques must result in a reaction torque exerted on the structure which supports it. The effects of this phenomenon for all elements must be considered.

DEFINING THE CHARACTERISTICS OF A SUB-SYSTEM
A gearbox may be considered to perform the same primary function as a belt/pulley system or a chain/sprocket system ie: that of transformation of torque and speed. All three consist of a number of components arranged as a sub-system. However for the purposes of specifying the total system the sub-system boundaries must be defined and then these sub-systems treated as system elements. In this way the 'transformer' characteristics are determined without reference to the type of transformer. Once they are defined a suitable 'transformer' can be selected.

CHARACTERISTICS TO CONSIDER IN ELEMENT SELECTION
The following two tables show a selection of the characteristics which should be considered for two common system elements. The list can be extended and adapted for other elements-

MOTORS:

RATED POWER ROTOR INERTIA COSTS

RATEDTORQUE INPUT SUPPLY TYPE RELIABILITY

RATED SPEED EFFICIENCY LIFE

STARTING TORQUE REVERSABILITY MAINTENANCE

PULL-UP TORQUE TYPE OF ENCLOSURE NUMBER REQUIRED

PULL-OUT TORQUE MOUNTING TYPE SUPPLIERS

MAX SPEED SHAFT SIZE SAFETY

MIN SPEED DIMENSIONS -

MAX INPUT POWER - -

GEARBOXES:

RATED POWER SHAFT SIZES LUBRICATION LIFE

MAXTORQUE SHAFT ARRANGMENT MAINTENANCE RELIABILITY

MAX INPUT SPEED MAX DIMENSIONS BACKLASH COSTS

MAX OUTPUT SPEED GEAR FORM REVERSABILITY NUMBER REQUIRED

RATIOS REQUIRED INERTIA NOISE SUPPLIERS

- SHAFT LOADING SAFETY -

- MOUNTING TYPE - -

RATED POWER	ROTOR INERTIA	COSTS
RATEDTORQUE	INPUT SUPPLY TYPE	RELIABILITY
RATED SPEED	EFFICIENCY	LIFE
STARTING TORQUE	REVERSABILITY	MAINTENANCE
PULL-UP TORQUE	TYPE OF ENCLOSURE	NUMBER REQUIRED
PULL-OUT TORQUE	MOUNTING TYPE	SUPPLIERS
MAX SPEED	SHAFT SIZE	SAFETY
MIN SPEED	DIMENSIONS	-
MAX INPUT POWER	-	-

RATED POWER	SHAFT SIZES	LUBRICATION	LIFE
MAXTORQUE	SHAFT ARRANGMENT	MAINTENANCE	RELIABILITY
MAX INPUT SPEED	MAX DIMENSIONS	BACKLASH	COSTS
MAX OUTPUT SPEED	GEAR FORM	REVERSABILITY	NUMBER REQUIRED
RATIOS REQUIRED	INERTIA	NOISE	SUPPLIERS
-	SHAFT LOADING	SAFETY	-
-	MOUNTING TYPE	-	-