GB2061438A - Locking Cotter Pin - Google Patents

Abstract

A cotter pin is provided with a captive retaining loop 5 of resilient wire opposite ends of which engage rotatably in non-coaxial holes 4 in opposite faces of the head of the pin; when moved into its retaining position the loop is forced over the end face 6 of the shank to snap-engage in a shallow transverse groove 8 in the end face 6, the loop 5 being retained in this locking position by friction. The groove 8 may be omitted. <IMAGE>

Description

SPECIFICATION Locking Cotter Pin This invention relates to cotter pins.

A form of cotter pin is widely used in agricultural machinery which has a captive retaining loop opposite ends of which engage rotatably in holes in the head of the pin, the loop being rotatable into engagement with the shank to prevent withdrawal of the cotter pin in use.

An object of the present invention is to provide a cotter pin having a simple means of locking the retaining loop in engagement with the shank. It is known to provide the shank of a cotter pin with a notch in which the retaining loop engages. The provision of such a notch for locking the retaining loop necessarily weakens the shank of the cotter pin, and usually entails a precision machining operation on the cotter pin after its manufacture.

The cotter pin according to the present invention comprises a shank having a head at one end, and a resilient retaining loop, the ends of which engage rotatably in holes in the head, the loop being rotatable into engagement with the shank, to prevent withdrawal of the cotter pin in use thereof, in which the loop in its retaining position engages an end face of the shank remote from the head, locking the loop by friction.

Since the retaining loop engages the end face of the shank in order to lock the loop in its retaining position it is not necessarily to subject the shank itself to any subsequent machining operation after manufacture of the cotter pin to provide the loop-locking facility.

The end face of the shank preferably has a transverse groove bounded by a shoulder such that in moving into its locking position the retaining loop is forced over the shoulder and snap engages in the groove. The groove may be formed during the manufacture of the cotter pin without necessitating a subsequent machining of the shank of the pin.

The invention will be further described by way of example, with reference to the accompanying purely diagrammatic drawings, in which, Figure 1 is a perspective view of a cotter pin according to embodiment of the invention, and Figure 2 is a side elevation of the cotter pin shown in Figure 1.

The illustrated cotter pin 1 has a cylindrical shank 2 formed with a head 3 at one end. The head 3 has non-coaxial holes 4 in opposite faces in which the end of a resilient retaining loop 5 engages rotatably. The retaining loop 5 can be rotated about the head 3 between an open position shown in Figure 2, in which the loop 5 is swung clear of the shank 2, and a closed position, shown in Figure 1, in which the loop engages the end face 6 of the shank 2 remote from the head 3, effectively locking the loop by friction. The closed or retaining position of the loop 5 is shown in broken outline in Figure 2.

When the retaining loop 5 is in its open position the shank 2 of the cotter pin 1 can be inserted in a transverse bore at the end of a cotter 7, shown in broken outline in Figure 2. The retaining loop 5 can then be swung into its closed or retaining position over the end of the cotter 7 the loop 5 being shaped, in a known manner, to permit such movement without obstruction by the cotter. By engaging the ends of the retaining loop 5 in non-coaxial holes 4 in the head 3 the loop is subject to a torsional stress which urges the loop 5 towards the shank 2 and therefore assists in holding the loop 5 in its closed or retaining position.

The end face 6 of the shank 2 is formed with a shallow transverse groove 8 bounded by a shoulder 9 over which the loop 5 may be forced in order to snap-engage in the groove 8. The shallow depth of the groove 8 is such that when engaged in the groove the retaining loop 5 is still under tension, so that it is effectively locked in the groove 8 by friction. The shoulder 9 is rounded as shown in Figure 2, to facilitate the forcing of the loop 5 over the shoulder 9 into the closed or retaining position.

Frictional locking of the returning loop 5 in engagement with the end face 6 of the shank 2 may be achieved without necessarily providing a groove in the end face 6.

Claims

1. A cotter pin comprising a shank having a head at one end, and a resilient retaining loop the ends of which engage rotatably in holes in the head, the loop being rotatable into engagement with the shank, to prevent withdrawal of the cotter pin in use thereof, in which the loop in its retaining position engages an end face of the shank remote from the head, locking the loop by friction.

2. A cotter pin according to Claim 1 in which, the end face of the shank has a transverse groove bounded by a shoulder such that in moving into its retaining position the retaining loop is forced over the shoulder and snap-engages the groove.

3. A cotter pin according to Claim 1 or Claim 2, in which the ends of the retaining loop engage rotatably in non-coaxial holes in opposite faces of the head.

4. A cotter pin substantially as herein described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Locking Cotter Pin This invention relates to cotter pins. A form of cotter pin is widely used in agricultural machinery which has a captive retaining loop opposite ends of which engage rotatably in holes in the head of the pin, the loop being rotatable into engagement with the shank to prevent withdrawal of the cotter pin in use. An object of the present invention is to provide a cotter pin having a simple means of locking the retaining loop in engagement with the shank. It is known to provide the shank of a cotter pin with a notch in which the retaining loop engages. The provision of such a notch for locking the retaining loop necessarily weakens the shank of the cotter pin, and usually entails a precision machining operation on the cotter pin after its manufacture. The cotter pin according to the present invention comprises a shank having a head at one end, and a resilient retaining loop, the ends of which engage rotatably in holes in the head, the loop being rotatable into engagement with the shank, to prevent withdrawal of the cotter pin in use thereof, in which the loop in its retaining position engages an end face of the shank remote from the head, locking the loop by friction. Since the retaining loop engages the end face of the shank in order to lock the loop in its retaining position it is not necessarily to subject the shank itself to any subsequent machining operation after manufacture of the cotter pin to provide the loop-locking facility. The end face of the shank preferably has a transverse groove bounded by a shoulder such that in moving into its locking position the retaining loop is forced over the shoulder and snap engages in the groove. The groove may be formed during the manufacture of the cotter pin without necessitating a subsequent machining of the shank of the pin. The invention will be further described by way of example, with reference to the accompanying purely diagrammatic drawings, in which, Figure 1 is a perspective view of a cotter pin according to embodiment of the invention, and Figure 2 is a side elevation of the cotter pin shown in Figure 1. The illustrated cotter pin 1 has a cylindrical shank 2 formed with a head 3 at one end. The head 3 has non-coaxial holes 4 in opposite faces in which the end of a resilient retaining loop 5 engages rotatably. The retaining loop 5 can be rotated about the head 3 between an open position shown in Figure 2, in which the loop 5 is swung clear of the shank 2, and a closed position, shown in Figure 1, in which the loop engages the end face 6 of the shank 2 remote from the head 3, effectively locking the loop by friction. The closed or retaining position of the loop 5 is shown in broken outline in Figure 2. When the retaining loop 5 is in its open position the shank 2 of the cotter pin 1 can be inserted in a transverse bore at the end of a cotter 7, shown in broken outline in Figure 2. The retaining loop 5 can then be swung into its closed or retaining position over the end of the cotter 7 the loop 5 being shaped, in a known manner, to permit such movement without obstruction by the cotter. By engaging the ends of the retaining loop 5 in non-coaxial holes 4 in the head 3 the loop is subject to a torsional stress which urges the loop 5 towards the shank 2 and therefore assists in holding the loop 5 in its closed or retaining position. The end face 6 of the shank 2 is formed with a shallow transverse groove 8 bounded by a shoulder 9 over which the loop 5 may be forced in order to snap-engage in the groove 8. The shallow depth of the groove 8 is such that when engaged in the groove the retaining loop 5 is still under tension, so that it is effectively locked in the groove 8 by friction. The shoulder 9 is rounded as shown in Figure 2, to facilitate the forcing of the loop 5 over the shoulder 9 into the closed or retaining position. Frictional locking of the returning loop 5 in engagement with the end face 6 of the shank 2 may be achieved without necessarily providing a groove in the end face 6. Claims

1. A cotter pin comprising a shank having a head at one end, and a resilient retaining loop the ends of which engage rotatably in holes in the head, the loop being rotatable into engagement with the shank, to prevent withdrawal of the cotter pin in use thereof, in which the loop in its retaining position engages an end face of the shank remote from the head, locking the loop by friction.

2. A cotter pin according to Claim 1 in which, the end face of the shank has a transverse groove bounded by a shoulder such that in moving into its retaining position the retaining loop is forced over the shoulder and snap-engages the groove.

3. A cotter pin according to Claim 1 or Claim 2, in which the ends of the retaining loop engage rotatably in non-coaxial holes in opposite faces of the head.

4. A cotter pin substantially as herein described with reference to and as shown in the accompanying drawings.