The Craftmans Shop > New from Old
It's BIG, Yellow and digs holes! JCB 3CX Project 8 is joining the Tractor Shed
awemawson:
It's certainly quite a beast - acording to Wikapedia it can fire a 45 kg projectile 14 miles :bugeye:
https://en.wikipedia.org/wiki/155_mm_gun_M1
Today I de-rusted, sand blasted and heavy zinc primered the 'return to dig' attachment that was fitted to the recently re-sealed ram. Essentially as the ram moves, a rod co-axial with a mounting tube operates a heavy duty microswitch that cuts off the rams motion when the bucket is at the correct angle if the operator puts the control lever across into a detent.
Tube and microswitch mount got a coat of red oxide primer, and the rod got sprayed satin black which is how it will stay.
Yellow RAL1007 on the tube & microswitch mount will be applied later this evening with a second coat tomorrow.
awemawson:
I gave the return to dig parts a coat of JCB yellow with the rod remaining black.
Next job: pull machine out of barn to where there is room to swing the dipper full left right to give the slew pots a final tighten with a 10 foot scaffold pole. Only problem, drivers seat which should swivel to let you use the rear controls was totally stuck.
Then followed a couple of hours pulling the seat out, finding that the main central shoulder bolt that holds the seat down was too short, so when the seat is turned it tightened the bolt clamping the seat. Five minutes of lathe work produced a captive spacer and another lengthy period of contortions putting the seat back :bang:
After that actually doing what I had intended and torquing the eight slew pot bolts was trivial.
awemawson:
At long last I've been able to re-mount the 'Shovel Reset' or as it's sometimes called 'Return to Dig' assembly on the shovel ram.
This is a simple but very cunning mechanism that once you have tipped a load from the front bucket, automatically returns the shovel to a horizontal position ready to scoop the next load. The left hand (shovel) control spool has a magnetic detent that holds the spool in the 'I'm coming back up' ie far left, until a microswitch on the mechanism mounted on the hydraulic ram trips dropping the detent and allowing the spool and lever return to the neutral position.
In my case the microswitch wasn't playing fair - always open circuit. Now they come as a plug, cable form (moulded into the microswitch) and Honeywell microswitch with a roller ended lever operating arm and are hugely expensive. Opening the microswitch failed to allow me to resurrect it and the only 'none JCB Spare' equivalent micro switches were equally stupidly expensive (actually slightly more!)
So I ordered up a genuine spare but when it arrived it was faulty :bang: Replacement arrived overnight and worked fine so that is what I fitted this morning. A bit of nifty lacing of the cable form to avoid it being sliced as the rams move and not only is it fitted - it works :clap:
The mechanism is clamped by jubilee clips round the hydraulic ram and unfortunately I rather scratched up my new paint but it'll touch up when next I have an open paint pot.
The idea is to set the 'detect' position to 'shovel level' so a few iterations with a spirit level got it to an acceptable setting.
Before the switch had arrived I'd tested the circuit to make sure that the wiring was OK and that the magnetic detent solenoid worked (paperclip replacing switch!) In these tests the coil was drawing 1.1 amps which seemed reasonable but the control wasn't being retained fully left. Now the engine was not running so no hydraulic pressure but I'd have expected the shovel spool to be clamped. Now it's back together it works so I can only assume that it uses hydraulic pilot pressure somehow.
. . but hey . . .it works !
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