The scrap metal hoist thread.

Hydraulic cylinders on normal machinery might not be as well made as you might hope, depending on the quality and the application. I have had a few apart and repaired them. Most agriculture and similar rams like the hoist are just seamless steel tube with a hone finish. The rods are usually hard chromed to repel dirt. But even on back hoes and the like a dissemble, clean and new seals will get them leak free and working ok even if the rods are a bit scored. The cylinders are normally ok if the dirt did not get in or water pooled in there. After all the things should be full of oil when operating.
Keep the water off the seals would be my recommendation !
cheers. jaahn
 
Alternative, and not beyond your capabilities, is the replacement of the whole Cylinder itself ! and perhaps grease or preservative oil on the upper area of the new one to prevent corrosion between extensions. Where there is a will there is a way!

Ken
 
So its been a while, I did buy a seal .... australia post managed to loose it ... It took ebay nearly 2 months to decide ..... Yes it really is lost, so I ordered another and it was here within a couple of weeks .... even over the xmas period. It arrived 3 days after it would have been really handy. You see I realised (or should I say I was reminded .... again .... for maybe the hundredth time .... the middle child was going for her license .... NEXT Monday :eek:).

She was reading through the list of checks they do before the test .... She got upto "test windscreen washers" .... which got a big "Merde!" from me, as they haven't worked in years, I've looked at them a couple of times and just got really aggravated and decided, who needs the damn things either way ? She also needs the ABS and ESP working too .... and those rollbar droplinks that have been rattling like crazy for years ..... while I'm there. So really usefully I have a hoist that doesn't work .... A set of full length car ramps sitting outside under a tree ... but a trolley jack and axle stands. About now, I found you have to drop the damn petrol tank just to change the ABS sender ( bloody poogoe! ). On the positive side, I did take a good sized chunk of flesh out of my face on a razor sharp cut off cable tie under the car.

Now obviously, the day after her test, the 2nd attempt at getting a seal for this hoist was successful :dance:

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I put the tallest, heaviest car here on it ..... It can lift considerably higher up between the shed purlins here. No sign of leakage too. So finally I can work on the stupidly low poogoes again if needed.
 
DoubleChevron said:
Probably, look at the size of the seal though. A car hoist isn't rated for constant use. Even in a commercial environment, they would go up and down .... a dozen times a day? compared to say a ram on an excavator, that would be in constant movement.

I have run a hone up and down it, its mostly quite clean below the "return" hole at the top of the ram (that will prevent it lifting to high). There is probably 3cm of sealing surface along the sides of the seal (rather than a fraction of a millimeter from an Oring).

It will be interesting to see how long it works for. I'm pretty sure it would work fine for now even with the probably 50year old heavily worn seal re-installed. With a new seal, it will hopefully outlive me :)

Worst case, I find another scrap metal hoist and start another project :ROFLMAO: There was a molner 4post with two sliding jacks last week on fb marketplace for~$1000. I would just put my existing pump on it ......

seeya
Shane L.
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Hi.

Typically Flex-hones are used to clean up the sealing surface on hydraulic cylinders. They do a good job.

There are many different designs and materials used for piston & gland seals, bearings and wipers, its a bit neiche, but can be interesting to understand the small variations needed for different applications. There used to be several seal suppliers with offices in Australia, they can supply any seal if you supply the dimensions of the machined cavity.

If you need, contact me, as there are local people who can supply and machine new barrel for the hydraulic cylinder.

Cheers.
 
jaahn said:
Hydraulic cylinders on normal machinery might not be as well made as you might hope, depending on the quality and the application. I have had a few apart and repaired them. Most agriculture and similar rams like the hoist are just seamless steel tube with a hone finish. The rods are usually hard chromed to repel dirt. But even on back hoes and the like a dissemble, clean and new seals will get them leak free and working ok even if the rods are a bit scored. The cylinders are normally ok if the dirt did not get in or water pooled in there. After all the things should be full of oil when operating.
Keep the water off the seals would be my recommendation !
cheers. jaahn
Click to expand...
Hi jaahn.

My understanding is the hard chroming of the cylinder rods is mainly as a more durable wearing bearing surface and also to reduce/prevent rusting. The oil floods the microcracks in the chrome and seals the carbon steel from oxygen. Hence the need to cycle the rods every now and again to wet them with oil. It's the gland wiper that removes dirt from the rod.

Cheers.
 
Whippet said:
Hi jaahn.

My understanding is the hard chroming of the cylinder rods is mainly as a more durable wearing bearing surface and also to reduce/prevent rusting. The oil floods the microcracks in the chrome and seals the carbon steel from oxygen. Hence the need to cycle the rods every now and again to wet them with oil. It's the gland wiper that removes dirt from the rod.

Cheers.
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these rams look to be built like junk to me. It looks like a length of standard mild steel tube. they use a big chunky seal to ride over any flaws in the steel. Nothing hardened. You could make it yourself probably. Actually, not junk. Its probably 50years old and still going strong. Its a car hoist, it never needs to worry about wear, heat, cold, duty cycle etc. There really is no duty cycle requirements for a hoist, so you dont' need fancy high wear proof parts. Its all just mild steel from what I can tell. Ram, piston .... well the entire thing :)
 
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