I have been asked some advice by a mechanic from another company who doesn't have huge experience on hydros . He has just inherited a 5 stop Inground that was originally otis but has recently been partially modded with a smartrise controller . He did the annual tests with the inspector and when he tried running up onto the stop ring he hit the ceiling before the ring . I told him I have never Personaly done it but I believe the answer is to sleeve the piston and advised him EECO or similar could machine the sleeves for him but the issue is with it being in ground how does he know what length of sleeve to use ? He could be 1 inch off hitting the stop ring or 3 feet , how would he know ?
All I could think of was to measure how far he is overtravelling to hit the ceiling deduct six inches from that and that's the length for the initial sleeve , then also have a number of two inch sleeves made to add if required .
I'm guessing someone else on here must have come across this situation ? Am I missing a trick ?

I would delve into this a little. Was the original specs for a future floor, or did they leave the stop ring off because the Piston rubs the Cylinder near the bottom, or it is hitting a section where the cylinders are welded together. Also if the original Jack was installed before 1972 it doesn't have a double Bulkhead. Just a few things to consider.

All things to consider , he says the original install was 92 and from the way he described it it sounds like a Otis welded head cylinder and has evac ports so it should be double bottomed . The building is a car park and as far as I know it would not of been a provision for extra floor . However I didn't even consider it may not have a stop ring or stop ring removed . I presumed they either ordered wrong size piston or the building was shortened between ordering materials and construction . I have had the opposite a few years ago where they extended a building by 4 foot after ordering the elevator ! . Now how to tell if he has a stop ring ? Hang the car near the top and pull the piston as I he was going to replace it see if he can pull it up enough to see or run something down to see I he can feel one ? I suppose that would give him an idea of where it was too and how much he needs to add ?

There might be enough room between the piston and jack cylinder to either send down some 1/2" ridge pipe, small stiff copper tubing or maybe even a soft flexible tape with a weight. When either of these is bottomed out at the bottom of the cylinder you could pull it out and measure to get a length. You would of course have to land the car and pull the head off to see if you have the clearance between the piston.

This over travel situation can be dangerous, there was a guy at another company in my area that ordered a jack incorrectly and actually ran the car literally right through the roof when he went to do the inspection! There are some pics floating around online.

Luckily I have never had it happen to me yet , just the opposite where the contractor changed the height of the building by raising it several feet . The construction guy who came down to do the install found that out pretty early into the job . I have heard of it happening a couple of times in this region tho .

Hang the car as high as possible then hang the piston with another jack clamp.Make sure you mark the jack so you will know your difference from as high as you can hang the car vs your six to seven inches of runby till you should hit the stop ring. Now you can remove the head. Measure down to the stop ring. Do your math twice to be sure you have the right distances figured out. Put everything back together and land car on pipe stands and lower piston and remove the head like you were going to repack. Have a piece of pipe cut that is just big enough to slide over the piston on the inside and just big enough to fit inside the bottom flange of your head and of course long enough to match you distance yo need to reach from your old stop ring to where you want it to hit now. This could be a couple inched to 12 foot if there was a future floor. Make sure you jack stands are long enough to math or you may need a couple sections of pipe if you have a jack with several future floors. We have done this in the past. Just slide the pipe over the piston. Ours was snug enough it didn't just drop down. So when we put the head of the jack back on we just ran the car up till the pipe bottomed on the stop ring and we were done.

I agree with Dan. Nice work!

Thanks Dan , sounds like a plan . The only bit I'm unclear of is the part where you initialy hang the car and clamp the piston , I'm fine with that . Then depressurize everything to pull the head to take the measurement to the stop ring , in doing this you would destroy the packing no ? Everytime I have repacked an Otis welded head jack I have had to pull the old packing with a T-bar with a screw end. If you have to do this to get the measurement then when you put everything back together and re pressurize to remove the hoists and clamp to let everything back down to land the car on pipe stands don't you have oil pissing everywhere due to the damaged packing ?
Also I guess the sleeve has to be made by someone like eeco as I would have thought it needed a machined Finnish similar to a piston in case it slides up and down in travel ?

So worst cast you go thru an extra packing and just look at it as a cost to do the repair. This would be a billable for anyone unless its the company that installed the jack in the first place. We have a good union machine shop we keep very busy here in town. With a dozen mod crews and a couple repair crews we are having custom plates made all the time. Also machine work on shafts, bearing pressed on and off ect ect all the time. I just assumed a relation ship with a machine shop was something all elevator companies had. A good machine shop is faster and cheaper than sending things out. Pieman we first worried it might travel up and down but it didn't . Slid right to the bottom and stayed there. Good Luck

Thanks Dan , its not the cost of the packing that was the worry ( I told him to order two sets of packing anyway ) it was making sure there was a controlled descent after taking the measurements and before landing on the stands , which thinking about it there should be even if the packing is damaged .
As for machine shops, we are on an island in the Caribbean . We have two . One completely useless and one ridiculously expensive and more for ornate gate work and architectural stuff. We have to ship in everything to be honest.
Thanks again for all the great advice , I will pass it on to the mechanic doing the job.