Ed's 77 Terex 72-41

[mountainguyed67]

We went up today, checked if fluid was enough to start it. There’s a petcock that’s supposed to have fluid at least that high before starting, it did. I started it and checked transmission pressure gauge, it was in the green. I then drove it forward and reverse, doh! Maybe the gallon we added did the trick, but it took time.

 

[mountainguyed67]

We tried to magnetize the solenoid by pulling the trigger, nothing. Then we put the wire that’s supposed to bring power to the solenoid directly to the battery 24v, nothing. Then we also put the ground wire to the battery, it magnetized a little. My son said when he really squeezed the alligator clip lead to the ground wire, it magnetized stronger. We put the solenoid back together and tried it with the grapple hoses connected, it still moved the tilt cylinders. I used the really tiny gauge wires that came with the controller, now I’m thinking it needs thicker gauge to make the magnet work.

 

[56wrench]

Was the diverter valve already on the loader when you got it or did you add it on? I don’t remember if you said

 

[mountainguyed67]

Was the diverter valve already on the loader when you got it or did you add it on?

I added it, it’s in this thread.

 

[56wrench]

Ok, what voltage is the coil on the solenoid rated for? What gauge are the wires to the solenoid?

 

[mountainguyed67]

I don’t know either of those.

 

[56wrench]

Post some close-up pictures of the diverter valve and the ports.

 

[mountainguyed67]

I don’t have pics like that.

 

[56wrench]

Did the valve come with any plumbing instructions or schematic? What is that square looking silver thing plumbed in to the right side of the valve?

 

[mountainguyed67]

What is that square looking silver thing plumbed in to the right side of the valve?

Solenoid.

 

[mountainguyed67]

Did the valve come with any plumbing instructions or schematic?

This is all I have.

 

[56wrench]

The coil on the end of the valve should actuate the internal spool in the valve. Be aware that some newer controllers have small wires and the microswitches may not be able to conduct much amperage therefore the controller may have to be wired to a relay which would then activate the coil on the valve. Somebody correct me if i’m wrong but most of the reliable systems i’ve seen have been wired through a relay.

 

[John C.]

They only time I put relays in is for big work light circuits.

 

[Nige]

I suppose it all depends on the current draw of the solenoid.

 

[56wrench]

The NH combines i used to work on had relays in the circuits for the electro-hydraulic stack valves so they must have drawn a fair amount of juice, even the low use circuits. Plus, its easier to change a relay than take apart some of those controllers to replace a switch

 

[Nige]

The NH combines i used to work on had relays in the circuits for the electro-hydraulic stack valves so they must have drawn a fair amount of juice, even the low use circuits.

A number of Cat electrical schematics I've been looking at recently had instances of solenoids being actuated via relays.

 

[mountainguyed67]

Be aware that some newer controllers have small wires and the microswitches may not be able to conduct much amperage therefore the controller may have to be wired to a relay which would then activate the coil on the valve.

Thanks, I hadn’t considered that.

 

[mountainguyed67]

What is that square looking silver thing plumbed in to the right side of the valve?

Do you mean the one mounted separately, and has a line coming in each side (left & right) and a plug on top? That’s part of the original plumbing.

 

[mountainguyed67]

The pin length will reach through, the bushings aren’t worn enough to get the pins through. One or the other will have to be machined, I’m thinking of opening up the bushings.

 

[56wrench]

Do you mean the one mounted separately, and has a line coming in each side (left & right) and a plug on top? That’s part of the original plumbing.

ya, that one. It doesn’t look original. Maybe a circuit relief valve?