Locking Pin

Linch pins and shaft locking pins

A linch pin (often spelt lynch pin) is a pin with a hinged spring ring, made for quick connecting and disconnecting of parts to an axle or pin. It retains a wheel or other rotating part on its axle, and is used to attach tractor implements, secure trailer couplers, camper trailers and tray backs, and on mining and haulage equipment. On farms it is the everyday pin that keeps 3 point linkage pins and implement pins in place on tractors and slashers.

A shaft locking pin, also called a retaining D clip, is a pin with a wire loop that snaps over the shaft. Hobson describes it as an anti-vibration way to secure the end of a shaft, for round and square tubes, on agricultural equipment, trailers and caravans. We carry D type and square patterns.

Which locking pin?

• •Linch pin: for axles and implement pins that are taken on and off often. Zinc yellow from 4.5 to 11mm, 316 stainless from 4.2 to 7.5mm.
• •D type shaft locking pin: a D shaped wire loop. Zinc yellow in 6, 8 and 10mm, 35 to 100mm long; 304 stainless in 6, 8 and 10mm x 55.
• •Square shaft locking pin: a square wire loop. Zinc yellow in 6, 8 and 10mm x 55.
• •Need a permanent pin that is bent over? Use a split pin. For a pin with a separate clip, see hitch pins and R pins; single coil R clips are on the split pin page.

Linch pin and locking pin sizes

Size is the pin diameter: choose the pin that fits the hole drilled through your shaft or axle. For the zinc yellow linch pins Hobson also gives the usable length A (as a guide only), for example 32 to 35mm on the 4.5 x 36 and 66 to 67mm on the 11 x 70: choose an A that suits the shaft the pin passes through. Measure an old pin or the hole, then match it to the table.

Zinc yellow or stainless?

• •Zinc yellow passivate: zinc plated (about 5 microns) with an iridescent yellow finish. More corrosion resistant than clear zinc plating, but still a low corrosion finish, recommended for low-corrosion conditions.
• •304 stainless (A2): corrosion resistant right through, with no coating to wear off. Our 304 range is D type shaft locking pins.
• •316 stainless (A4): adds 2 to 3% molybdenum, the change made so stainless would hold up by the sea. Our 316 range is linch pins.

How to fit a linch pin or locking pin

1. Line up the hole through the shaft, axle or pin.
2. Push the pin through the hole by hand.
3. Swing the ring or wire loop over the end of the shaft until it snaps into place, so the pin cannot slide out.
4. To remove it, pull the ring or loop back off the shaft and draw the pin out by hand.
5. Replace any pin with a bent pin, a weak or broken spring ring, or heavy corrosion.

Linch pins in Adelaide

Allmat supplies linch pins, locking pins, split pins and hitch pins to farmers, contractors, mechanics and trade across Adelaide and South Australia. Add them to a quote with the rest of your list, and we will price the lot.

Questions