Who understands PTO hydraulic tipper decks?

[Unclejake]

Folks, I'm a bit out of my depth here. I bought a half fucked 2003 Isuzu NQR truck and don't know how to test the tipper.

• The clutch line is blown, so although I can start the truck in gear and drive it around in that gear (only) I can't disengage the clutch at this time. A new clutch line is two weeks away
• All the brake lines and fuel lines have rusted through, but that's probably not relevant right now.
• At one point the truck had a rotary broom on the front. That has been removed and the hydraulic hoses simply joined together behind the front bumper. From what I can see the broom worked on a 24v hydraulic pump mounted to the side of the chassis. You can see the white plastic reservoir behind the Hiab i the below photo 
• There's another pair of hydraulic hoses coming from the Hiab and the steel undertray hydraulic tank that I THINK are also joined together behind the front bumper (it's really hard to see)
• The truck currently has most of a Hiab fitted, but the Hiab is missing the boom and is very rusty. I don't care about the Hiab and want it removed
• I care about the tipper. The ram is under the deck and is a single action(?) ram. The ram only has one hydraulic hose that goes from from the top of under-tray hydraulic  tank to the ram... but that hose has burst.
• There's a big hose that goes from the bottom of the tank to the PTO. The pressure hose on the PTO goes to some kind of valve arrangement that I am struggling to see with the tray down. It's a mystery at this point.
• There's a red lever inside the cab that operates a cable that seems to engage or de-engage the PTO
• The hydraulic system includes the PTO, a hydraulic cooler, numerous electric solenoids, an electric switch bank in the cab to divert oil to either the hoist or the broom
• There's an under tray hydraulic tank with numerous hoses coming out of the top of it via electric solenoids. There is no filler cap on the tank (and I can't tip up the deck for a better look)
• It looks like the under-tray tank gets filled via the Hiab hydraulic tank, which will be a problem when I delete the Hiab

So... what I'm hoping to do is throw away the Hiab, delete all the spare hoses and solenoids, delete the 24v pump, cooler etc. etc.... and simply run a pressure hose from the PTO to the tipper ram. I figure that'll make the ram go up?

What I don't understand (and I've got no clutch at the moment so can't experiment) is how the deck would come down again. Is it as simple as slipping the clutch?

Finally: I'd like to be about to spread 'metal, along the driveway as I drive. Am I about to make that impossible?

FML I know NOTHING about tipper trucks. I've never used one. LOL

 

 

[Hemi]

The tipper ram line should end up at a divertor valve should have pressure, neutral/ both closed and in your case a feed back to the tank to let the deck down. 

Without seeing a full layout it would be a bit hard to help more then that. If you find the diverter, even if they are electric it *should * have the ability to be mechanically actuated in case you lose electrical power with the deck in the air. Depends who set it up tbh. 

[Unclejake]

Shit. Thanks Hemi. I think I need to get someone with a working Hiab to pull the tray up. It's a rats nest of hoses and valves that are bloody hard to see with the tray down.

[Unclejake]

20 minutes ago, Hemi said:

The tipper ram line should end up at a divertor valve should have pressure, neutral/ both closed and in your case a feed back to the tank to let the deck down. 

 

Should I be seeing an electrical switch on the dash to let the tray down then? I'm heading back to the truck in about an hour so can get more photos

Also: Can I test any of the PTO hydraulic circuit without using the clutch?

[h4nd]

Wild arse guess: Any chance of stuffing the 24V pump into the Ram for an empty lift to get to the rest of the wiring/tubing hoo ha under teh deck?

[rusty360]

Ram will just be single acting as tipper deck doesn't go over center. Will just have a valve to let oil flow to ram then the spool will move and let the oil go back to tank.

[Unclejake]

I can't get the 24v pump to do anything unfortunately. Wet as hell here so I haven't been under the truck this afternoon. 

Fuck resizing images on an Android phone is a ballache. I'll have to sort out the photos from the laptop tonight.

With the ignition on but the engine stationary I can get something to make a thud noise when I turn the broom raise knob, but impossible to know what's thudding by myself. I need an assistant. 

Still very keen to know if any of this effort is useful without a clutch though 

 

[Unclejake]

[rusty360]

Normally you need to push the clutch in to engage the pto to drive the hydro pump. 

[Unclejake]

That would explain a few things.  Thank you.

At risk of sounding stupid: Can I pull up the red lever with the engine off, start the engine and then expect to see hydraulic-oil pissing out of the fitting where I removed the blown tipper ram feed hose?

 

[rusty360]

I'm not 100% sure how the system works you got. But normally you would engage the pto which would get the hydro pump running, then move a lever or switch that controls the hydro valve - that would then let the oil fill the ram and lift the deck.

The tipper control might be electric over hydraulic?

[rusty360]

41 minutes ago, Unclejake said:

That would explain a few things.  Thank you.

At risk of sounding stupid: Can I pull up the red lever with the engine off, start the engine and then expect to see hydraulic-oil pissing out of the fitting where I removed the blown tipper ram feed hose?

 

What does that red handle lever connect to? 

[MaxPower]

Can start a truck with the pto engaged , ones at work we do anyway if the air pressure has been built up. Is it stuck in gear? Could always drop the driveshaft if you really want to try it out. You will need to have a good hose from your pump to your ram before doing anything else first. 

[Hemi]

Yes, as long as the pump is not loaded you can start it with the PTO engaged and it should work fine

[Hemi]

1 hour ago, Unclejake said:

That would explain a few things.  Thank you.

At risk of sounding stupid: Can I pull up the red lever with the engine off, start the engine and then expect to see hydraulic-oil pissing out of the fitting where I removed the blown tipper ram feed hose?

 

If the diverter/ associated spool valve is in the correct position yes.

[Hemi]

29 minutes ago, rusty360 said:

What does that red handle lever connect to? 

It engages the PTO by the looks

[Hemi]

To play elimination. Red lever engine PTO in neutral, start truck. Sound like you have something working with the thud, this could just be lines pressurising and flailing about could also be trying to do something. The white box would control the main divertor valve. Broom and tipper are powered by the PTO by the sounds and maybe the hiab was* powered by the pump. The pump could also just be and emergency thing/ added later. I would highly doubt the electric pump would be powering the broom itself as that would kill the battery even running in not much time. Would power a hiab just fine though. 

Back to where I was. Red lever up/ engaged . Truck running in neutral white box switched to hoist and then flick between and up down and see what happens. Perhaps check after each click to see if oil starts being produced somewhere.

[Hemi]

1 hour ago, rusty360 said:

Normally you need to push the clutch in to engage the pto to drive the hydro pump. 

Push to break drive so you can engage* PTO needs drive through the gearbox to operate so clutch mist be in the " relaxed" /drive position. I read this and got confused for a sec so clarifying

[Hemi]

Given there are so many circuits that 100% been fucked with being able to see the control bank would help heaps. 

Tbh I'd do the above and see what happens and go from there. 

[mjrstar]

The 24v pump might just have rusty connections or a dead solenoid.. I'd be tempted to see if it has any life in it direct via jumper leads.. 

A decent 24v pump if low geared enough might have the balls to lift the deck depending on ram diameter. 

 

EDIT: That red lever is almost certainly an ejector seat handle.