A. Shaft
has two male ends which can move in either direction throughout the casing. Under torque load, the shaft will move towards the
power input end until the shaft end fitting "bottoms out" on the out side of the
female mating part or on the inside of the female form depth. The engagement of the
opposite end should be approximately 1-1/4" under normal conditions. If the mating
female is 1.50" to 1.63" deep, allowance is provided for growth or contraction
of 1/4" to 3/8" without bottoming" (column-loading) or disengaging the
shaft.
B. A
shaft has one male end and one "retained" end. In this case the
"retained" end should be at the power input end of the shaft. This will allow
the driving end to move as illustrated in "A" above.
C. Shaft
has two female or "retained" ends. This construction has the built-in problems
of:
1.) loading the casing when the shaft
shortens, which increases the drag and wear between the shaft end fittings and casing;
2.) column-loading the shaft when it extends,
which could contribute to degradation of the assembly.
Conditions A & B above should always be used if their design can be
accommodated because they allow the shaft to be removed and inspected for wear, damage or
re-lubrication. Also, excessive inter-reaction between the casing assembly and shaft
assembly can be avoided.
