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Who understands PTO hydraulic tipper decks?


Unclejake

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Thanks a million team. I just got into wifi range so photos from this afternoon have suddenly appeared in the thread. 

One photo is less obvious than the others. It's the top of the hydraulic-oil tank and shows what I assume must be the electric over hydraulic valves mentioned by others. 

No sign of air in this truck. Red lever is attached to a morse style cable that runs to the PTO. If I lift the lever when the engine is running there's a graunch noise (makes sense now). The gearbox feels OK. 

Wiring has been damaged by rats and from sitting for two years. Additionally,  some local chaps were trying to 'fix' the wiring for the previous owners in 2022. I have removed a little of that wiring which has now made the engine run. Yay!

Incredibly; The engine didn't even make a full rotation under the starter before it burst into life and went straight to a steady idle. The engine and chassis are very sound

I'll try Hemi's diagnostic plan ASAP. I will need someone else with me to crank the engine whilst I watch for things happening 

 

SERIOUSLY appreciate all your input.  Amazing information for a numpty like me. Thank you 

EDIT: Freight alone to get a truck this size to the island would be about $8k, so it's worth making a bit of effort on. I reckon replacing the brake, clutch,  and fuel fluid lines could take two full days,  but bundy tube is pretty cheap 

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I (of course) have the advantage of seeing at least some of the circuit in real life (impossible to photograph)and I suspect the cooler has been installed to cool 100% of the system (apart from the 24V pump).

@rusty360's idea of pushing the spool (I didn't know that was a spool) by hand will be awesome tomorrow.

Above the big hose to the PTO is a black steel tank that seems very robust. I wonder if it's designed to hold pressure?. I guess not, but I'm not sure. That black steel tank doesn't appear to have a filler.... but the Hiab does have a filler and an orange  tank,  and it looks like the orange Hiab tank has a gravity fed hose that feeds the black tank. The orange tank is empty. I dunno what's in the black tank.

Unfortunately the hydraulic hoses in and out of the 24v pump are smaller than all the other hoses, and evidently this complicated system worked two years ago before one hose 'blew' (read: It wore out from dragging onto the gravel roads) so I figure I'll get a guy in with another Hiab to tilt the deck up, replace the 'blown' hydraulic hose, fly in some hydraulic-oil, repair the wiring as best as I can.... and then use @Hemi's "start the engine with the PTO engaged" approach.

If it's all a disaster I'll have wasted my money and time and will tow the truck to my property, dig a big hole and bury it. Seriously I will.

But if the deck goes up and down I'll sort out all the brake lines etc. and drive around the island tipping shit wherever I like. LOL!

 

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If you just want to test it engine oil will do the trick. I have done this many times on breakdowns with zero I'll effect.

That's not the same as saying service you excavator and using engine oil is fine.

But if it's cheaper and easier. It's fine

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51 minutes ago, Unclejake said:

I (of course) have the advantage of seeing at least some of the circuit in real life (impossible to photograph)and I suspect the cooler has been installed to cool 100% of the system (apart from the 24V pump).

@rusty360's idea of pushing the spool (I didn't know that was a spool) by hand will be awesome tomorrow.

Above the big hose to the PTO is a black steel tank that seems very robust. I wonder if it's designed to hold pressure?. I guess not, but I'm not sure. That black steel tank doesn't appear to have a filler.... but the Hiab does have a filler and an orange  tank,  and it looks like the orange Hiab tank has a gravity fed hose that feeds the black tank. The orange tank is empty. I dunno what's in the black tank.

Unfortunately the hydraulic hoses in and out of the 24v pump are smaller than all the other hoses, and evidently this complicated system worked two years ago before one hose 'blew' (read: It wore out from dragging onto the gravel roads) so I figure I'll get a guy in with another Hiab to tilt the deck up, replace the 'blown' hydraulic hose, fly in some hydraulic-oil, repair the wiring as best as I can.... and then use @Hemi's "start the engine with the PTO engaged" approach.

If it's all a disaster I'll have wasted my money and time and will tow the truck to my property, dig a big hole and bury it. Seriously I will.

But if the deck goes up and down I'll sort out all the brake lines etc. and drive around the island tipping shit wherever I like. LOL!

 

So in a normal system the hydro tank will be under zero pressure. It will be just feeding the big boy pto pump I'd say.  And the ram etc will feed Back into it. If you can get some pics of the control valves with the deck up it shouldnt be to hard to work it out. 

 

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Some good news: The thudding I was hearing when operating the broom up or down switch came from two different valves (spools?) at the top of the black hydraulic tank. The only bad news is that those spools operate regardless of ignition switch position... so I figure that's why the previous owners had so much trouble with flat batteries. 

I reckon the two different spools thudding bodes well and confirms what you fine chaps thought: The system is electric over hydraulic. 

I didn't start the engine as it gushes out too much diesel onto the ground and I don't have much spare hydraulic fluid.... but the mechanic will repair the damaged pressure hose in the next few days. 

Another bloke is coming with a Hiab to lift the deck soon too. We will see which of them gets their job done first! Ha

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Sorry, late to the party here, yes the switching all suggests that its elctric over hydraulic. 

you will need to have the motor running and engage the pto before you start it, the newer trucks run a button ont he dash for PTO engagement and light up on the dash and button when engaged. 

the thud u heard could have been any residual pressure int eh line between the spool valve and the item it swtiches, but yes great it means that some things are working at least.  the spools to clunk a bit if hard mounted when they activate.

 

it very much looks as though you have a good project on your hands. they are all quite simple but it really doesnt help when there has been a bunch of penis fingers in there lately making a mess of it all to work things out, like you have mentioned getting the basics worked out like power properly switched with relays and the other mechanical items sorted first will mean you can work through it easily.

 

 

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I’m gonna guess that’s an ex downers truck cos of the yellow color and its location 

the 24v pump was probably just for up on the broom cos it prob ran a snowplough half its life - no need for stop / pto in / raise plough just electric up gravity down when solenoid opens 

have seen a few where the hoist is off the 24v pump also but not the broom rotate function 

with the combo of hoist broom and hiab it must be a total rats nest of hoses but hey remove what ya don’t want and may get some spare hoses for what you need 

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It was Downer for certain and 24v pump for broom up and down only makes absolute sense now you mention it.

I'll start deleting the spare hoses etc. after confirming the hoist works in its present configuration. I'm too scared to modify anything hydraulic prior to getting to a known state.

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