TABLE 2 USE FACTORS FOR THE TORQUE RATING OF UNIVERSAL JOINTS
Intermittent
Running Conditions
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Continuous
Running Conditions
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5.1 Example 2 Universal Joint
Selection for Continuous Operation
A single universal joint is to transmit a continuously acting torque of 20 in-lbs., while
operating at an angle of 15° and at a speed of 600 RPM. Select a suitable joint.
From Table 2 for continuous operation, the use factor Is
given as 68. Note that there are blank spaces in the table, If the combination of
operating angle and speed results in a blank entry in the table, this combination should
be avoided.
The required torque is (68) (20) = 1360 in-lbs. There is no shock load and the dynamic
factor of 2 does not
apply in this case.
From the catalogue, it is seen that there are two joints
meeting this specification: 508-0500 and 508—D516, both with a torque capacity of
1700 in-lbs. The first has a solid-shaft construction and the second a bored construction.
The choice depends on the application.
5.2 Example 3: Universal Joint
Selection for Intermittent Operation With Shock Loading
A single universal joint is to transmit 1/4 horsepower at 300 RPM at an operating angle of
15° Select a suitable joint for intermittent operation with shock loading.
Here we make use of the equation:
Torque = Horsepower x 63,025 in-lbs.
RPM
Hence, operating torque = ( 0.25) (63,025 ) = 52.5 n-lbs. From Table 2, for
intermittent
(300)
loads (300 RPM, 15°), the use factor is 16. Due to shock loading
there should be an additional dynamic factor of 2.
Hence, the rated torque = (52.5) (16) (2) = 1680 in-lbs. Thus the
same joints found in the previous example are usable in this case.
5.3 Example 4: Determining the
Maximum Speed of an Input Shaft
A universal joint is rated at 250 in-lbs., and operates at an angle of 12°, driving a
rotating mass, which can be represented (together with the inertia of the driven shaft) by
a steel, circular disc, radius r = 6”, thickness t = 1/2",
attached to the driven shaft, How fast can the input shaft turn if the inertia torque is
not to exceed 50% of rated torque?
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