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Randaleky 
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Joined: 17 Aug 2011
Location: belfry, ky.
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 Topic: hyd. pump
Posted: 07 Jun 2016 at 10:19pm |
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hey folks, I just installed a gas 3.5 hp engine to an hyd pump in order to operate the boom lift, and extend jacks on an altek bucket lift. the hyd works fine raising and extending the boom, problem is when lowering or retracting the boom the engine is stalled out and quits. if you barely crack the valve lever you can lower and retract the boom , but it seems as though back pressure is stalling the engine. any ideas ? thanks randal
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DMiller
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Joined: 14 Sep 2009
Location: Hermann, Mo
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Posted: 08 Jun 2016 at 6:43am |
You will need more HP for a ALTEC boom. The way these work is the hydraulics lock to keep the boom and extensions in place when in use to eliminate drift, the system has to basically power down thru the locked up hydraulics unloading the check ball system while applying pressure on both sides so it will controllably move the booms/cylinders.
I work at a utility that uses a lot of ALTEC equipment, was a wrench on these for over 30 years.
ALTEC is abbreviation for Alabama Truck Equipment Company, now manufacturing in I believe six states.
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Dozer
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Location: SW New York
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Posted: 08 Jun 2016 at 7:03am |
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When you lower something that you raised hydraulically faster than you raised it you are passing greater oil volume. If the flow is suddenly stopped the oil pressure can spike higher than allowable system pressure. The cure would be to add a flow restriction as you are doing by just cracking the return valve.
Choosing a over pressure relief valve would cause the bucket to drop dangerously fast.
Likely the volume of the hydraulic system is too small for the task
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DMiller
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Posted: 08 Jun 2016 at 12:40pm |
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Not the way the ALTEC systems work, the down pressure is ported to a check ball on the up side and vs a vs, when you select a direction you are porting oil to a release for the opposite direction but is restricted by the pressure being applied. Very simple for safe operations with a human in a man basket but takes a lot of hydraulic effort thus more hp required.
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Randaleky
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Joined: 17 Aug 2011
Location: belfry, ky.
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Posted: 08 Jun 2016 at 2:11pm |
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thanks, If the hydraulics are strong enough to quickly raise the boom and extend the boom without bogging the engine down, and it takes pressure to release the ball up or down, when why is it slow when lowering or retreating the boom extension to the point the engine will choke off, and if you barely crack the lever to lower the boom it will come down very slowly ? I would think with plenty of pressure to raise that lowering would pressure would be enough. thanks randal
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farmtoybuilder
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Location: Dresden,Ohio
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Posted: 08 Jun 2016 at 2:43pm |
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Yes a lot more hp. for it to work.
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5 different TT-10's,5 TT-18's Terra Tigers,B-10,2 B-207's,B-110,2 B-112's,HB-112,B-210,B-212,HB212,2 Scamp's & Homilite T-10. Still hunting NICE HB-112 & anything Terra Tiger & Trailers for them.
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Randaleky
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Posted: 08 Jun 2016 at 6:18pm |
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i checked the pressure and it takes 500 psi to raise and 1500 psi to lower and the motor can not sustain the pressure so it chokes off. What size H P do any of you recommend ? thanks
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DMiller
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Posted: 08 Jun 2016 at 8:33pm |
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These are generally run from a truck belt driven (engine)PTO, I would consider minimum HP at 15 or twenty. Up is not as necessary as to interlock as down, you do NOT want a uncontrolled decent while sitting in a man basket thus the cross pressure and the increased cross pressure.
Edited by DMiller - 08 Jun 2016 at 8:33pm
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wayneIA
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Location: Waverly, IA
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Posted: 08 Jun 2016 at 9:06pm |
A lot of man lifts, and even cranes run the load check valve like what DMiller is talking about, two fold on the reason, first is like what DMiller said on the controlled decent, second prevents the boom from dropping if the raise line would fail. The HP requirement would be based on how many GPM you are moving with your pump. Here is a page telling how to calculate it, I believe they are calculating for the electric motor requirement, so you would want to upsize a gas engine a little (if you calc. 7.5 HP go to 9 or 10). http://www.engineeringtoolbox.com/hydraulic-pumps-horsepower-d_1464.html
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Randaleky
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Posted: 08 Jun 2016 at 9:18pm |
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I appreciate all the information i have received. i will study the chart and figure out what hp i need. thanks to all of you. randal
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