PTO Question

Glenn Warner · Nov 8, 2013

Hi Guys,
Got an 84 GMC General that was originally a tandem axle dump truck ,that was converted to a
vacuum pumper/ water truck by a fire dept. We bought it off the fire dept when they upgraded
last year to a new pumper/ tanker. we are having trouble burning up the bearings in the vacuum pump.We think the real problem might be a high
speed PTO that is over revving the pump.we have 2
other vacuum pumpers which run much slower but still build up vacuum as required. Any ideas or suggestion to try.

showcrop · Nov 8, 2013

fire tanker trucks, even converted oil tankers, normally have a PTO driven centrifugal pump that pumps the water. It is usually primed by a gear pump that is run by a starter motor. I don't know about how the vacuum pump would fit in.

jm. · Nov 8, 2013

Glen I know when you go to order a NEW PTO for a truck you can get several speeds relative to the engine speed. Like one that runs 50% of engine speed on up to like 150% so yes you could have a pto that is turning too fast. Should be a tag on the pto and you can da a search for the folks that made it.

DeltaRed · Nov 9, 2013

Back when I worked in a 'diesel shop',we installed/replaced many truck PTOs.They all looked the same but had diffewrent gear ratios.I dont remember them being too expencive.Call a couple truck shops,truck parts,dealers..... for priceing

cjd12000 · Nov 9, 2013

Dont quite know what it looks like but all are milking equipment vacuum pumps have oiled bearings. If it just pulling air then they should be oiled either reclaimed or refilled as needed.

RodinNS · Nov 9, 2013

I don't know anything about the pump in your application... but general things about vacuum pumps... such as the old Surge Alamo's... they have pressure lubricated bearings and sometimes the feed tubes that supply oil to those bearings will get blocked and need cleaning. That's something to consider if it has pressure lube. Beyond that all I can suggest is that you get the model/serial numbers off both the pump you're using and the PTO setup and take those to the respective manufacturer's reps or search online and see what the recommended speed is for the pump and what the output of the PTO is. I can tell you that a PTO could be spec'd at as little as mabey 50-75% of engine speed and probably as high as 200% of engine speed depending on what was required at the time. Obviously if you have a PTO on the higher end and the pump wants to turn somewhere on the lower end, problems will result...

Other than that... I'm kind of curious why you would go with a vacuum tank vs a midship style of pumper/tanker?

Rod

PTO Question

Glenn Warner

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showcrop

Well-known Member

jm.

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DeltaRed

Well-known Member

cjd12000

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RodinNS

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