55 ton brake press pump psi info

I have a hydra-power press brake model 55-10. Today I tried to bend 8 foot of 3/16 mild steel and it will not even begin to bend. My question is what
psi should the pump be putting out? Under load my pressure gage reads 800 p si which seems very low to me. Machine is at least 40 years old and I'm jus t looking for conformation that I need to rebuild the pump. I'm not sure of the maker as I am having a hard time finding it online. Serial number is 6 55047860. Machine works great under less load
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On Wed, 3 Jan 2018 07:23:32 -0800 (PST), Deanne Porter
I don't know the answer, but I know who probably does. Hydra-Power was a Di-Acro brand. They sold it to Pacific Press Technologies three decades or more ago. Pacific Press will troubleshoot over the phone for those old machines, so you can give them a call:
800-851-3586
--
Ed Huntress

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On Wednesday, January 3, 2018 at 9:36:38 AM UTC-6, Ed Huntress wrote:

ot of 3/16 mild steel and it will not even begin to bend. My question is wh at psi should the pump be putting out? Under load my pressure gage reads 80 0 psi which seems very low to me. Machine is at least 40 years old and I'm just looking for conformation that I need to rebuild the pump. I'm not sure of the maker as I am having a hard time finding it online. Serial number i s 655047860. Machine works great under less load

Thank you for the info Ed
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On Wed, 3 Jan 2018 07:40:18 -0800 (PST), Deanne Porter

Good luck with it, Deanne.
--
Ed Huntress

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On Wed, 3 Jan 2018 07:23:32 -0800 (PST), Deanne Porter
Sounds like the press has a dual pump circuit that's not working properly. The pump has two stacked sections; a low displacement and a high displacement pump in one package. At low pressure/force both pump sections are working giving a fast advance. When the pressure rises, the high displacement pump's output gets dumped back to tank and you get high pressure and low speed. There's probably a sequence valve (or two) that do the switching. The valves could be part of the pump, but more likely are are external. My bet is that there's something wrong with the valve(s).
If it's a fancier than normal press, it may have a variable displacement pump that's not reducing displacement in response to rising pressure.
--
Ned Simmons

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On Wed, 3 Jan 2018 12:10:18 -0500, "Jim Wilkins"

Yes, that's an example of a pump with integral valving. The sequence valve I spoke of is on the left side of the hydraulic schematic on that page. When the pressure at the outlet overcomes the spring (zig-zag on the bottom of the valve) the large pump's flow returns to tank (inlet on the schematic). The schematic of a circuit with discrete pump and valves will be very similar.
--
Ned Simmons

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I have a hydra-power press brake model 55-10. Today I tried to bend 8 foot of 3/16 mild steel and it will not even begin to bend. My question is what psi should the pump be putting out? Under load my pressure gage reads 800 psi which seems very low to me. Machine is at least 40 years old and I'm just looking for conformation that I need to rebuild the pump. I'm not sure of the maker as I am having a hard time finding it online. Serial number is 655047860. Machine works great under less load
===============2500 PSI is a common rating for low-cost pumps and cylinders, such as on log splitters and small bucket loaders. https://www.justanswer.com/heavy-equipment/4fhyr-bobcat-hydraulic-pressure-cylinder.html
I've seen advice to choose a pressure gauge rated at twice the working pressure, so that's a clue.
If 55 is the tonnage and 10 the length you could figure the pressure from the cylinder diameter.
-jsw
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On 04-Jan-18 12:54 AM, Jim Wilkins wrote:

Would 800PSI x (Area of piston) give you the force being generated?
Comparing that value to the 55 ton spec might give some info too.
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