Question concerning a 75H Dake Shop Press (Bore size?)

I wasn't really sure where to ask this question but figured I'd try here. Does anyone know the bore size of a 75H Dake shop press. I have one of these presses that no longer has the factory gauge that is calibrated in Tons. I just have a pressure gauge on mine and would like to be able to calculate the tonnage for a given pressure. Was hoping maybe someone here may know.

Thanks,
Jeff

Can't answer your question, but you might be able to get the right gauge from Dake.

Sent from my SM-G950U using Tapatalk

4.37 bore would get you 75 tons at 10,000

The math...

Dake says 75 tons = which is 150,000 lbs

Press makers sometimes liked to limit the pumps to 10,000 PSI

150,000 divided by 10,000 = 15

15 square inch piston would be 4.37 dia

Because 4.37 X 4.37 X .7854 = 15

If some other upper limit on pump pressure redo the math for a differing bore

Here is manual, call them up and ask questions.

https://www.dakecorp.com/uploads/pdfs/manuals/75H-2019.pdf

Have fun

The housing on a 75 ton Dake is a lot larger than I think they would use for a 4.37 bore, so I suspect the pressure is a lot less than 10,000 psi.

gbent said:

The housing on a 75 ton Dake is a lot larger than I think they would use for a 4.37 bore, so I suspect the pressure is a lot less than 10,000 psi.

Click to expand...

I would agree that it appears to be larger. I was wondering if anyone had the original gauge as sometimes I have seen them list the ram size on the gauge but not sure if Dake did that or not.

Andy FitzGibbon said:

Can't answer your question, but you might be able to get the right gauge from Dake.

Sent from my SM-G950U using Tapatalk

Click to expand...

I believe that gauge is likely available but judging by the price on a couple I seen for sale online its more than I really wanted to invest on a gauge.

Well, I knew fifty years ago, but not any longer. We had a 75T air-powered Dake in the axle engineering lab where I worked. I wanted a more accurate gage for roughly measuring ram force to do various things on axles. So I ordered a large diameter precision gage that had only the usual PSI scale. I calculated the pressures for the 1000 pound force intervals and used a Letraset transfer set to add the force scale next to the PSI scale. Of course, we had electronic load cells and the Tinius Olsen tensile test machine for really accurate work.

The press is in the left rear of this picture. Windows 10 does not seem to respect my orientation command, but you can save and print it if you like it.

Larry

Just about 3 years ago I had a Dake 75H follow me home.
The leather piston cup was in bad shape.
After watching this video I made a replacement.
As I recall the OD of the leather cup was 6"

Yep, 6.18 is double the area of 4.37 - making pump maximum 5000

Here is a picture thats worth several words and a bunch of math.

Exactly the information that I was looking for. Thank you Lazz! I would like to have the factory gauge but not quite enough to pay the price. The gauge that's on it works just fine. Now that I know the size I can figure the tonnage myself.

I would not have thought leather seals would be good for 5,000 psi.

I changed the seals on my Dake 50 ton, the gauge reads in tons for a 5” ram. The large size of the housing is for the oil reservoir.

An interesting fact I found out about the 50 ton size is that it can produce 50 tons of pressure but its actual working range is best at up to 25 tons. I had to make a longer handle when I needed to use a fairly high pressure, just above 30 tons, the frame seemed like it was not quite up to the task of going to the full 50.
It was also quite a chore to pump it over 30 tons, needed a lot of force on the lever.
The good thing is the longer your cheater bar the farther away you are from the danger zone......

I added a small hydraulic pump to my press and it was only capable of 1800 psi, which translated directly to 18 tons under the ram. So the hand pump is capable of 5000psi. (which still works) The electric pump is a very nice addition to the press and I rarely need more than 18 tons for my work.

I am pretty sure I read about a PM’er who added a quick change system with a variety of gauges to his press so he could use the press for very low pressures, the tonnage gauge on mine is useless for light work. I have usually overdone it before the gauge needle moves. I did add an adjustable pressure relief valve and that works very well to do consistent bending.

In fact leather buckets are good for 10,000 psi ,and they have the strange property of allowing water to bleed ,but sealing oil at high pressure....The good old Servex presses (30/60 /100/200 ton ratings)can survive decades in a lean to ,or even out in the yard with a half of a drum over the works ...and still work reliably every time you rebuild your dozer.....All the Servex presses have cast iron cylinders,and Ive never seen one disabled by rust in the bore.