jeffl1107 Posted February 6, 2011 Share Posted February 6, 2011 Hey guys,Was not sure where to put this so hope it is ok. Wondering if any of you guys know if there is somekind of valve on a hydraulic piston that lifts the dump body on a dump truck somewhere that can control how fast or slow the dump body comes back down after i dump a load. Right now it takes forever to come back down. I just had everything rebuilt about 5 months ago. Just wondering cause I would like to speed it up if possible. Thanks, Jeff Quote Link to comment https://www.bigmacktrucks.com/topic/17864-hydraulic-piston-question/ Share on other sites More sharing options...
Bollweevil Posted February 6, 2011 Share Posted February 6, 2011 Hey guys,Was not sure where to put this so hope it is ok. Wondering if any of you guys know if there is somekind of valve on a hydraulic piston that lifts the dump body on a dump truck somewhere that can control how fast or slow the dump body comes back down after i dump a load. Right now it takes forever to come back down. I just had everything rebuilt about 5 months ago. Just wondering cause I would like to speed it up if possible. Thanks, Jeff First of all, did it ever at any time work properly? If it did, your problem probably is not valving. Sometimes, the cylinder packing will swell, and as the pressure bleeds off, the hoist will stay up. Try raising and lowering the hoist several times while loaded. Sometimes as the hoist cylinder wears, the hoist will fowl on uneven ground, and it wont come down till you get level. Quote Link to comment https://www.bigmacktrucks.com/topic/17864-hydraulic-piston-question/#findComment-72304 Share on other sites More sharing options...
RowdyRebel Posted February 6, 2011 Share Posted February 6, 2011 If it is cold, the oil may be flowing like molasses. A thinner hydraulic oil in winter months might help. Quote When approaching a 4-way stop, the vehicle with the biggest tires has the right of way! Link to comment https://www.bigmacktrucks.com/topic/17864-hydraulic-piston-question/#findComment-72305 Share on other sites More sharing options...
hatcity Posted February 6, 2011 Share Posted February 6, 2011 If possible-get larger diameter hose. Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment https://www.bigmacktrucks.com/topic/17864-hydraulic-piston-question/#findComment-72308 Share on other sites More sharing options...
theakerstwo Posted February 6, 2011 Share Posted February 6, 2011 And some times the large bore cylinders with alummin beds are just slow. My freind that runs two trucks in front of me has a 20 ft bed built from alummin triler that we so tire of. It takes so long and we have to wait cause when he moves with bed up no one wants to watch.He has had it in the shop a few times for this they say the hoist is just to long and large. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/17864-hydraulic-piston-question/#findComment-72310 Share on other sites More sharing options...
Rob Posted February 7, 2011 Share Posted February 7, 2011 Hey guys,Was not sure where to put this so hope it is ok. Wondering if any of you guys know if there is somekind of valve on a hydraulic piston that lifts the dump body on a dump truck somewhere that can control how fast or slow the dump body comes back down after i dump a load. Right now it takes forever to come back down. I just had everything rebuilt about 5 months ago. Just wondering cause I would like to speed it up if possible. Thanks, JeffSounds to me like you have a smaller orifice diameter in the dump valve than you like. These restrict the flow of oil from the cylinder on the return to tank. Most of these can be pulled and another installed for desired speed. On a single hose system the orifice restricts both the extension and retraction. Hydraulic pressure easily overcomes this restriction on the extension cycle. With a two line setup, the orifice restriction will only be in the retraction line.If it were mine, I'd pull the orifice and leave it out but install an adjustable hydraulic restriction valve. These install in the oil path and you adjust it to the speed you want it to operate at. After adjustment, lock it in place and should never need adjusted again unless you install another floor and need to slow it down a bit due to empty weight. Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/17864-hydraulic-piston-question/#findComment-72326 Share on other sites More sharing options...
fifth wheel Posted February 7, 2011 Share Posted February 7, 2011 If you have a Commercial pump on there you need to add a return line from the valve to the tank. On most single acting systems they plug this port, and when the spool is in the body down position the oil has to pass back through the pump and suction line to the tank. If the body is light it will still drop slow.FW Quote Link to comment https://www.bigmacktrucks.com/topic/17864-hydraulic-piston-question/#findComment-72331 Share on other sites More sharing options...
bobo Posted February 7, 2011 Share Posted February 7, 2011 If you have a Commercial pump on there you need to add a return line from the valve to the tank. On most single acting systems they plug this port, and when the spool is in the body down position the oil has to pass back through the pump and suction line to the tank. If the body is light it will still drop slow.FWdoes it have a filter? they are plumbed on the return side it could be plugged? did you check the vent? bobo Quote Link to comment https://www.bigmacktrucks.com/topic/17864-hydraulic-piston-question/#findComment-72333 Share on other sites More sharing options...
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