BACKGROUND OF THE INVENTION
Yokes for universal joints in which torque is transmitted between a hub and the yoke by a bolt loaded in shear are well known. In such yokes, the bolt extends through the hub and the yoke parallel to the axis of rotation and offset therefrom. If the torque capacity of the yoke is exceeded, the bolt fails by being sheared off and the hub and yoke are then free to rotate independent of one another.
In prior yokes, the bolt normally extended beyond the hub or yoke. Even if the yoke was originally provided with a bolt that did not extend too far beyond the surfaces of the hub and yoke, once sheared, the bolt was often replaced with any convenient length, even if longer than the original bolt. Such bolts become positively driven projections in service as they can catch clothing or human parts and generally create a hazard.
SUMMARY OF THE INVENTION
This invention provides a shear joint for torsionally coupling a hub element to a yoke element with a shear bolt and an associated nut which eliminates a shear bolt as a positively driven projection and hampers improper repair using an excessively long bolt. One of the elements has means for capturing the head of the bolt against movement toward the other element with the bolt offset radially from and parallel to the rotational axis of the assembly. The other element has a first passage which opens toward the one element to receive the bolt. A second passage adjoins the first passage and is laterally larger than the first passage to define a shoulder facing away from the one element, the second passage being sized to receive a nut for the bolt with the nut tightening against the shoulder to draw the elements together. A stop means proximate to and facing the end of the bolt is provided which abuts the end of the bolt if an excessively long bolt is used to repair the joint. If such a bolt is used, it will not be possible to tightly connect the elements to one another, thereby discouraging use of an excessively long bolt.
Preferably, a T-shaped slot defines the first and second passages, thefirst passage being the longitudinal leg of the "T", the second passage being the lateral leg of the "T", and the stop means being the top of the "T" opposite from the end of the bolt. The slot extends radially from where it is in alignment with the bolt to the outer perimeter of the other element. The nut can be inserted into the outer end of the second passage for engagement with the bolt.
In a second embodiment, the first passage is a bore through the other element and the second passage is a recess surrounding the bore on the side of the other element opposite from the one element. The stop means in this embodiment comprises a member covering the recess over the bore, the recess having an uncovered open portion into which the nut can be inserted for engagement with the bolt. By making the bore oblong, after the bolt is sheared, the nut and remaining severed portion of the bolt in the nut can be removed from the bore.
In an especially preferred form, the one element is the hub and the other element is the yoke. By connecting the hub to the driving shaft, when the bolt shears, the yoke and the portion of the drive line connected to the yoke stops abruptly. By so stopping, centrifugal force tending to throw the nut and severed bolt out of the T-shaped slot is curtailed.
It is a principal object of the invention to provide a shear joint for torsionally connecting a yoke element to a hub element which reduces the risk of a shear bolt as a positively driven projection in the assembly.
It is another object of the invention to provide such a joint which hampers improper repair so as to avoid the shear bolt projecting from the repaired assembly.
It is another object of the invention to provide such a joint that can be economically manufactured.
It is another object of the invention to provide such a joint in a yoke/hub assembly especially adapted for connection to the power take off shaft of an agricultural tractor.
It is another object of the invention to provide such a joint that can be easily and economically repaired using a commonly available shear bolt and nut.
These and other objects and advantages of the invention will become apparent from the drawings, described below, and from the detailed description.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front perspective view of a yoke including a shear joint of the invention;
FIG. 2 is a rear perspective view of the yoke of FIG. 1;
FIG. 3 is a side elevation view of the yoke of FIG. 1;
FIG. 4 is a sectional view from the plane of the line 4--4 of FIG. 3;
FIG. 5 is a fragmentary perspective view of a second embodiment of a joint of the invention;; and
FIG. 6 is a sectional view from the plane of the line 6--6 of FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a yoke assembly 10 is illustrated which includes a shear joint of the invention. The yoke assembly 10 includes a yoke 12 and a hub 13. The yoke 12 has a pair of arms 15 which are adapted for connection to a cross or spider (not shown) of a universal joint as is well known in the art. The hub 13 has internal splines 16 for engagement with a drive or driven shaft, such as the power take-off shaft of an agricultural tractor. A locking collar 17 is also provided on the hub 13 to hold the hub axially on the drive or driven shaft as is well known.
本文转自：China Industry News