Making a JCB 3CX Slew Lock Plate

by John

I have a 35 year old JCB back hoe, a left over from when I grew olive trees and made olive oil. These days it is used only as a yard crane, and other small jobs on a 5 acre property. But since I am between model engine and cannon projects I decided to expend some TLC on the rather neglected JCB.

One feature which always made me grimace was the broken slew lock plate.

The slew lock plate supports the excavator boom and jib when the backhoe is driven between jobs. It takes the weight of the rear end, taking weight off the hydraulics. Unfortunately the old plate has been broken and re-welded so many times that it is IMO beyond repair.

A new plate is $AUD 1300 + GST I could not find a machine for wrecking, and was told that wrecked JCB 3CX’s are almost unknown, most owners, mostly farmers, keep them going for ever.

So I measured up the plate, drew it up on CAD, and had it laser cut from 20mm plate.

The laser cut bits. 20mm plate and 25mm plate hinges. Cost? $AUD 180

Deep V fillets were ground, and MIG welded.

Fitted to the excavator boom. I decided to not use the thin metal sloped flanges present on the original part, which I presume are to facilitate engaging the plate to the king post pin seen in the photo. I will engage the plate manually, by removing the securing pin (left) through the back hoe rear window.