Dust cap assembly having two snap ring securing mechanism in a slip spline assembly

#The invention relates generally to slip spline assemblies and more particularly to covers for closing the yoke bore ends of slip spline assemblies.

#Slip spline assemblies are used in heavy duty applications to transmit torque while allowing for axial translation between input and output components. A conventional slip spline assembly includes a slip yoke having a central longitudinal bore that receives a splined portion of a connection shaft. The internal splines of the yoke bore interfit with the splines of the shaft to provide for torque transfer between the yoke and the shaft while allowing for axial movement between the shaft and the yoke. Lubricant such as grease or other viscous fluid is often used and retained in the slip yoke bore to facilitate relatively smooth axial translation between the splined shaft and the slip yoke. The ends of the slip yoke bore are typically closed to maintain the lubricant within the bore and to prevent dust and other undesirable contaminants from entering the bore.

#To close the open end of the yoke bore, slip spline assemblies are commonly provided with dust covers. Various connections and retaining mechanisms have been employed to retain the dust cover in the yoke bore end. When lubricant pressure excessively builds-up in the yoke bore due to sudden axial translations between the shaft and the yoke, it is desirable that the dust cover operate as a mechanical fuse and selectively fail to release the pressure build-up. Otherwise, excessive pressure build-up can impede movement between the shaft and yoke and result in damage to components either within the slip spline assembly or other external drive components associated with the input and output of the slip spline assembly.

#These and other aims, objectives, and features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

#FIG. 1 is a prior art illustration of a dust cover assembly, illustrated in cross-section.

#FIG. 2 is a cross-sectional view of a slip spline assembly including a dust cover assembly according to a preferred embodiment of the present invention.

#While the invention is susceptible of various modifications and alternative constructions, a certain illustrative embodiment thereof has been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention as defined by the appended claims.

#Referring to FIG. 2, a dust cover assembly 20 retained in the yoke bore end 22 of a slip spline assembly 24 is illustrated in accordance with a preferred embodiment of the present invention. The slip spline assembly 24 generally includes a slip yoke 26 and a shaft 28. The slip yoke 26 has an internally splined longitudinally extending bore 30 slidably receiving an externally splined portion 32 of the shaft 28. The slip yoke 26 and shaft 28 can be conventionally connected to input and output drive components (not shown) in order to transfer torque therebetween while allowing for axial movement or misalignments between input and output drive components. To provide for smooth axially slippage between the shaft 28 and the slip yoke 26, the bore 30 is preferably filled with viscous lubricant such as grease. The dust cover assembly 20 covers the yoke bore end 22 to prevent contaminants such as dust, dirt or other foreign matter from interfering with the smooth translation between the shaft 28 and the slip yoke 26. At the other shaft end of the slip yoke 26, a conventional retainer seal assembly 33 including a cap and ring gasket is secured to the yoke 26 to prevent dust and contaminants from entering the yoke bore 30. The seal assembly 33 provides a relatively tight seal between the shaft 28 and the yoke to remove or scrape lubricant from the smooth portion 31 of the shaft 28 as the shaft 28 moves axially away from the yoke 26 and the smooth portion 31 exposes itself.

#As illustrated in FIG. 3, the dust cover 34 preferably includes a breather hole 35 that releases air pressure build-up caused by most normal operating axial shifts between the shaft 28 and the slip yoke. The breather hole 35 is small enough to prevent most contaminants and larger contaminants from entering the yoke bore 30 and to prevent leakage of lubricant from the bore 30. However, the necessary small size of the breather hole 35 does not provide a quick enough release for sudden pressure build-ups in the yoke bore. High lubricant/grease pressures and/or air pressures may result from large sudden axial movements between the slip yoke 26 and the shaft 28, or if the yoke bore 30 is too full of lubricant.