Help!! In-ground hoist issues, need advice ASAP!!

[coxy321]

I'm pretty desperate to get this sorted, so ANY help is appreciated!

At my parents house, we have an in-ground hydraulic hoist/lift similar to the one at the top of the page in this link:
http://www.manitowoclifts.com/manitowoc ... round.html

About 7 years ago the seals started to seep, and about 5 years ago they started to leak fairly badly, and the hoist started to become insecure (pressure leaking). So i disassembled the retainer plate, wiper seal, and removed what was left of the inner seals.

I drove 1hr to the only "local" hydraulic workshop (who will remain unnamed), and asked them to fix it, at whatever cost. I knew it was just seals, and seals cant be THAT expensive.

Anyway, long story short, it has taken this particular hydraulic workshop 5 years of me hassling them before they came and fixed it yesterday arvo - or so i thought.

Tonight i thought i'd re-assemble the top deck so i could use the hoist over the weekend - but when i tried to lower the shaft (its about 5' high ATM) - it didn't budge. I tried for an hour pumping air into the cylinder and wiggling it, but its just jammed up real good.

My reason for the thread and question is this, in the pictures below you will see the wiping seal, which appears to be squashed through to the top-side of the retainer plate. Firstly, i reckon that this has actually jammed the piston tight, and secondly it doesn't make sense for the seal to protrude because the top deck mates with the retainer plate when lowered all the way - and it has no recess for the "exposed" seal.







I dont know if anybody here is able to help me (possibly some of the older fellers that may have worked with these sort of hoists), but i just want to know if this IS installed wrong before i go and jump down this snapper-heads throat.

Cheers!!

[want33s]

I used to use one of them out at Eidsvold years ago. They are a simple long lasting bit of gear.
Yours doesn't look right. As you say the seal should be just lower than the groundplate.
The old guy I worked for was always onto us to sweep the floor away from the ram and not towards it so stuff could fall in the gap and score the seal or ram.
Good hoist for doing brakes and tyre changes on but a PITA for exhausts or gearboxes.
Jas.

[coxy321]

Done a bit of digging and found this:
http://automotiveshopequipment.net/page ... ng_Kit.gif

Looks like i'l be pulling it to bits again tomorrow, and hitting the workshop up for no charge on labour (cause he clearly has NO idea what he was doing - and they're supposed to be inground hoist specialists, my arse).

I should have questioned the fitment of the seal at the time - the amount of bullsh!t the guy was dribbling should have had alarm bells going off from the start.

Never again.

Coxy

PS. Havent got the bill yet, so that shall be VERY interesting!

[eliteforce32]

they have installed the o ring/seal wrong way round.... and now will be streatched... get a new one before any heavy lifting .

[bogged]

tell them to come out and look n fix it.

[coxy321]

tell them to come out and look n fix it.

I guarantee it will be another 4-5 years before i can get the bastards back!! I've got photos of it, so i'll fix it myself and just hit them for discount.

[ricky1970]

Do you have the old seals?????? Bit hard to tell from the pix, but maybe the wiper is the wrong profile causing it to grip the rod excessivaly hard. There are heaps of differant types of wiper seals available, and going by correct ID/OD alone is go garentee of sucess.

My bet is the wiper is wrong, the dia of the outer part of the housing (where the wiper is poking through) is too small causing the wiper to jam the rod. If this the case, use correct wiper (obviously) or machine housing correctly to take a differant wiper if origional is not available.

Is the main pressure seal a lip type seal? Did it roll during installation? Is it even the right size? If its old style rope gland packing (non graphite inpregnated), you may have to soak it in oil before installation.

They obviously didn't test it when they done it

[coxy321]

OK,

I do have the old seals, the pressure seals (four from memory, in a V shape) are absolutley rooted, got pinched and are in bits. I do have one old seal left, and it appears to be just a heavy rubber with a few oil bleed holes staggered around it.

The new seals are exactly the same, however they feel a lot stiffer than the old one.

The main presure seals were put in with plenty of care and patience, and the guy explained the rolling thing to me when he was doing it. they are definatley OK.

They had to use the old wiper seal and retainer spring as they couldn't find a match for it. The seal WAS in really good nick, however i am dreading the removal of it tonight.



This is how the seal SHOULD fit up. The piston is black, the retainer plate is blue, the seal is red, and there's a little yellow pressure spring in there on the seal.

I reckon if i pull the retainer up, seat the seal and spring, then lower the retainer back with the wiper seal square on the piston/retainer instead of pulled through, it should be ok.

I'll lube up the pressure seals while i'm at it too.

God, wish me luck......

Coxy

[ricky1970]

If the pressure seals are an inverted 'V' shape they are Vee packs and are usually housed with some preload on them (as opposed to a lip type seal where the housing is highter than the seal). If there is too much preload on them, they squash out and create a very tight fit on the rod. Most things use either an adjustable gland nut or shims to control this. If the top plate bears directly on the vee pack set and there is too much preload, you may have to shim the plate up tp create less preload.

If its not too hard to dissassemble/assemble, you could try removing the wiper and trying it to see if the problem is the main seal or the wiper.

rick

[coxy321]

Might do that too. He measured the recess, then put in enough seals to be just proud (i think) of the recess.

Just got the bill.... $1180.00

Including the $480 labour for the 45min he was there. Thats $640/hour.

Not bad for someone who clearly has no idea what they're doing.....

[bogged]

Might do that too. He measured the recess, then put in enough seals to be just proud (i think) of the recess.

Just got the bill.... $1180.00

Including the $480 labour for the 45min he was there. Thats $640/hour.

Not bad for someone who clearly has no idea what they're doing.....

instruct them to do what a duck cant do with it...

[chimpboy]

Might do that too. He measured the recess, then put in enough seals to be just proud (i think) of the recess.

Just got the bill.... $1180.00

Including the $480 labour for the 45min he was there. Thats $640/hour.

Not bad for someone who clearly has no idea what they're doing.....

instruct them to do what a duck cant do with it...

Hell yeah, that is outrageous. You can just about buy a hoist for that.

[Simo63]

Might do that too. He measured the recess, then put in enough seals to be just proud (i think) of the recess.

Just got the bill.... $1180.00

Including the $480 labour for the 45min he was there. Thats $640/hour.

Not bad for someone who clearly has no idea what they're doing.....

You would have been better off putting the money towards a new 2 or 4 poster. And whilst on this subject, I've heard that those old single posters are widow makers as they can just drop without any notice. Is that true?

[coxy321]

That depends. If you dont use the safety stop, maybe....

They have a solid steel shaft hinged onto the top deck so as soon as it lifts up, the bar drops down and it prevents the hoist from dropping.

When we decided to stop using the hoist, i had my MK SD33T wagon on it, and when it "let go", it just lowered itself at about the same speed it would normally go down when you crack the bleed valve. More than enough time to crawl/walk out of its way.

I have enough money for the repair, but not a whole new hoist. And given that the hoist/plumbing is already there and setup, i couldn't see the point in not fixing it.

I shall post my results tonight after i have a play. COMPLETE waste of time sealing up the outer ring with silicone last night - should have tested it first.

Coxy

[ricky1970]

Silastic and hydraulics are never a good mix anyway

[coxy321]

You can see it in the very first photo, but the silastic is just there to stop shit getting between the protective outer steel guard and the retainer plate. It isn't really "sealing" anything, just covering up the gap.

Well i had a play with the hoist this arvo. First thing i did was back off the retainer bolts bit by bit. Lucky i put the silastic, because it acted as a proof of the plates position. As i backed off the retainer bolts, the silastic started to tear apart - the plate was moving up.

After a bit of rooting around, i tried reseating the wiper seal, but it was no better than before, however...

I have decided that there is too much pressure from the retainer ring pushing down on the pressure seals, which in turn is creating too much friction on the piston. This means that i'm going to have to shim up the retainer plate about 3-4mm in order to allow enough pressure to hold the pressure seals on, and enough pressure hold the wiping seal in place. Another important reason for the retainer to be bolted down tight is cause the weight of the top deck (and Jesus bar [safety bar]) will be put i=on the retainer constantly, and it cant have any flex or slop.

I'm half tempted to put the GQ on it tomorrow for its service, but i wont.

Peace out.

[Shadow]

i dont know why your playing with it

if you want them to fix it, let them fix it. If you fuck around with it they can wipe thier hands of it and demand payment.

Simply call them, let them know you wont be paying for it till its fixed. $1180 is alot of money for them to fark around with not fixing it.