Resilient retaining rings such as "snap rings", "E-rings" and "C-rings" are employed to maintain the position of elements on a shaft or to maintain the position of elements within a bore. To facilitate removal and installation, some rings are formed with apertures at terminating ends by which a ring is engaged and then either expanded or contracted by a suitable tool.
Retaining rings are supplied as "internal" or "external". The external type are usually used to retain elements such as bearings, gears, or pulleys on shafts. An external ring normally engages an annular groove formed in a shaft to inhibit axial movement of a shaft mounted element. The external-type ring is installed by expanding the ring until its internal diameter is greater than the shaft diameter.
The internal type of retaining ring is used to retain an element such as bearings or shafts, within a bore. In order to install a ring it is contracted in order to pass into the bore and then allowed to expand to engage an internal groove formed around the bore.
Normally tools for installing and removing external and internal type retaining rings are substantially different. In the case of external rings, the tool must expand the ring to increase its internal diameter in order to clear a shaft whereas in the case of internal rings, the tool must contract the ring in order to decrease its external diameter to enable the ring to clear a bore. For this reason, retaining ring pliers are supplied as single purpose "external" and "internal" types. These single purpose pliers are each intended to remove or install one type of ring only and therefore a mechanic is required to have both types of pliers if he is to remove both external and internal rings.
In the past, dual purpose retaining ring pliers have been suggested or tried. In one proposed construction, the tool included a single pivot shaft, but two pivot holes. When the shaft was placed in one pivot hole, the tool acted as an external retaining ring plier and when placed in the other hole, the tool became an internal retaining ring plier. In order to switch between internal and external functions, the tool required disassembly.
In another construction, one handle of the retaining ring plier is articulated intermediate a jaw pivot point and the end of the handle. The handle also includes a movable link which in one position locks the one handle to prevent articulation and causes the tool to act as an internal type retaining ring plier. The link is movable to another position which allows articulation of one handle with respect to the jaw pivot point and causes the tool to act as an external retaining ring tool. The problem with this latter construction is that movement of the link changes the mechanical advantage so that the force needed to operate the tool is different when it was used in the "internal" mode compared to the "external" mode.
In still another construction, a pair of jaws is selectively engaged with a pair of handles utilizing axially movable pins. It is believed that the suggested construction is expensive to manufacture and changing from "internal" to "external" functions is cumbersome since movement of the relatively small pins is difficult and requires a separate tool to effect movement in the pins.
Many commercially available and proposed retaining ring tools include a removable tip. Clamping members associated with each jaw typically clamp the tip in a groove formed in the jaw and/or the clamping plate. The mounting arrangements must not only secure the longitudinal position of a tip, but in the case of angled tips, must also restrain or inhibit rotation of the tip with respect to the jaw. It has been found that with some prior art clamping arrangements insufficient clamping force is exerted on the tips to inhibit rotation when the tip is subjected to high retaining ring forces. Rotation of the tip within its groove can often damage not only the tip but the tool itself in addition to causing frustration to the user.
USPTO Backgrounds
USPTO Backgrounds