Governor with Two
Page 25
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Separate Spring Adjustments
Besides the Usual Means for Varying Tension, a . Device is Incorporated for Altering Spring Strength
rrENsioN and strength are two 1 important characteristics of governor springs, and it is desirable to be able to adjust them separately. Patent No. 548,211 details a governor, the invention of A. D. Draper and the Weyburn Engineering Co., Ltd., --Elstead, Surrey, in which the strength can be adjusted without affecting the tension and vice versa, thus fulfilling the requirements named above and as outlined in the specification.
The object is achieved by incorporating a mechanism °which alters the length of the operative part of the spring, in addition 'to an independent device for varying the tension. Concentrically positioned around the spindle (4) which is actuated by the governor weights (5) is the tension spring (I). It is anchored to the spindle at one end by a tension' adjuster (3), whilst its other anchorage is formed by a helical internal flange on a rotatable sleeve (2) having on its exterior a thread of preferably the same 'pitch as the spring.
This thread engages with the end of the governor casing and provision is made for locking the sleeve in any desired position, a setscrew (6) per
forming this function. .
In the accompanying drawing the sleeve is shown in the position for maximum strength, only about one coil being operative. By slackening screw 6, and screwing sleeve 2 to the right, further coils are brought into play and the effective strength of the
spring diminished,' this being done, given. similarity of pitch, withont altering the ,tension, which, supposedly, has already been set by adjuster 3.
This feature is perhaps more easily understood by visualizing the sleeve in use to increase instead of to lessen the spring strength. Kunming that there is no tension on the spring at all, the sleeve can be moved from the extreme right to the extreme left, subject as before to the pitch proviso, without creating any tension.
Clearly, the pitch of the spring is not constant, so that the device can be made to function at only one specific spring-tension value, but the ability" to do that satisfactorily meets requirements.