return to dig operation 450c

[Charlie]

Hi
can someone explain the operation of the back to dig operations? what takes place when the switch is operated? the wires were disconnected from the switch when I bought the crawler and I never reconnected them. what affect does the back to dig solenoid have on the hydraulics when power is applied?
Charlie. I think the correct term is return to dig

[Farmerford]

On my 455D the bucket control valve has a detent on the curl position that holds the valve in the curl position (ie, returning bucket from dump position) until 12VDC is applied to the solenoid located on the valve, at which time it is released from the detent.

The switch on the loader bucket link just completes the circuit when the bucket is level (ie, ready to dig). So, if the bucket has just dumped and you move the hydraulic valve control lever into the detent position, the bucket will begin to curl and the valve will stay in the curl position until the bucket link moves far enough to close the switch, which allows current to flow through the solenoid in the valve and release the valve from the detent, at which point the valve returns to neutral and the bucket stops curling. If you adjust the switch correctly, the bucket will stop curling at the right angle to dig the next load.

I may have the switch position backwards: I am not sure whether it opens or closes when the bucket returns to level, but the concept is the same: when the switch operates, the solenoid on the valve releases the valve from detent and it springs back to neutral, stopping the bucket movement.

[cdunn]

Farmerford, glad to know there is someone near by ( I live near Shiloh, about 30 miles north of you) who has an interest in JD crawlers. We'll have to talk more sometime.

[Charlie]

Thanks for the replies, now my question is if the switch stops the bucket curl, how do you get past it if you want to have more or less curl? I am going to reconnect the switch tomorrow and see if I can understand the operation better. thanks again

Charlie

[Farmerford]

The detent mechanism is holding the valve in the curl position, so you don't have to hold it in. When the switch activates, the detent releases the spool and the valve is returned to neutral by the spring. But if you continue to hold the valve lever in the curl position with your hand, the valve remains in the curl position even when the detent releases because you are holding it, and the bucket continues to curl. The detent and solenoid don't force the valve to neutral, they just allow the spring to shift it to neutral when the solenoid activates.