Hein Werner Model M

[ReEngineer]

Hi all,

I recently picked up a Hein Werner Model M, a 2 Ton long reach service jack. Given the age it's in decent shape and i'm trying to figure out whether or not to replace all of the seals.

It was low on oil so i topped it off. Havent observed any leaks overnight but since it needed oil, i'm sure they exist so i'll keep an eye on it.

Without a load the jack goes up all the way in 2-3 full pumps. With a load, it's extremely slow but does the job and it seems to stay up. My question is, does anyone know whether this is normal for this type of jack?

 

[PureLeaf]

Looks in pretty decent shape ! Nice going. Can't speak to the normal operation of an old Walker jack like that, wish I could find one of those myself.

Check out this thread though. Someone had similar questions as you for a Model M, and theres looks to be a link to a service manual. https://www.garagejournal.com/forum/showthread.php?t=79766

 

[ReEngineer]

Thanks! I went through many Hein Werner Model M threads before posting this up. I contemplated responding to the very thread you sent me but was weary of reviving an old thread.

Any advice would be greatly appreciated.

 

[ajchien]

Hi all,

Without a load the jack goes up all the way in 2-3 full pumps. With a load, it's extremely slow but does the job and it seems to stay up. My question is, does anyone know whether this is normal for this type of jack?

It’s a dual pump jack. Without getting into how the valves work, They’re trying to maximize Pascal’s law by giving you two modes of operation. With no load, it gives rapid lift with little force multiplication per pump; and with a load, it gives greater force multiplication with less lift per pump. Distance of lift and force multiplication are inversely related, so you can’t get both at the same time manually.

So, yes, normal operation does slow down when a load is applied. However, I’m not sure what you mean by “extremely slow”. How many pumps is it taking you to achieve whatever you’re trying to do?

 

[ReEngineer]

That's a great point. I was beginning to think that under no load the larger (presumably low pressure pump) or both pumps kicked in creating the large lift, then with a load only the smaller pump (identified as high pressure in parts breakdown) took over creating the high pressure and less lift.

I'll have to test it against another jack for comparison. I recently rebuilt a Hein Werner WS that would make a great comparison.

 

[Hiball]

That's a great point. I was beginning to think that under no load the larger (presumably low pressure pump) or both pumps kicked in creating the large lift, then with a load only the smaller pump (identified as high pressure in parts breakdown) took over creating the high pressure and less lift.

I'll have to test it against another jack for comparison. I recently rebuilt a Hein Werner WS that would make a great comparison.

That’s Exactly how it works, Both pump Pistons work from the start till the lift arm reaches a load. Once the lift arm encounters resistance, PSI increases to unsafe levels for the low pressure seals due to the increased cylinder diameter and the bypass valve opens up and dumps the oil volume back into the reservoir to prevent damage.

 

[ReEngineer]

Thanks Hiball! I appreciate the input.

Given that it does raise, hold a load, and hasn't started leaking; what would be some signs that this jack needs to be rebuilt?

 

[Hiball]

Thanks Hiball! I appreciate the input.

Given that it does raise, hold a load, and hasn't started leaking; what would be some signs that this jack needs to be rebuilt?

The fact that history of the jack is unknown + the age tends to put me in the go ahead and reseal it camp. I suspect that since it was low on oil, eventually a leak will rear its ugly head. With that said.. the jack uses Vee’s on the pump pistons so it’s possible that they just needed some adjustment to control some leaks and the PO addressed the issue, just never checked the oil level.

 

[ReEngineer]

You're probably right. I'm in no rush to rebuild, i may just wait to be able to get the kit through you once you're back up and running.

I'll report back on the raising comparison with the freshly rebuilt WS as soon as i get a chance.

 

[roblouvasz]

I just stumbled on this thread. I have rebuilt one of these jacks ( now I have 4 of them!) Anyway, from what I've seen, the main seal behind the lifting ram is what will fail first. The one I changed was ripped/ worn out. I found my kits on eBay. But there was another co. that had them but there's two different sized high pressure rams. Overall it's not that hard. The tricky part is changing the ram seal. The original is "stamped" on. I had my machinist modified it to accept a jam nut. PM if you have any questions. They're great jacks!