Hydraulic elevator

[fly258]

I was in a building  where they had a couple of external hydraulic elevators serving 4 floors. It would appear that the lift cars sat on long steel poles which were pushed up from the hydraulic rams and then sank back in on the downward journey.

If this is the case then surely the ram must be in a shaft sunk into the ground the equivalent distance of at least 4 floors with the associated pipe work and room for maintainence.

 Can anyone tell me if this is correct or is there a simpler way of doing it?

[Clanad]

The hydraulic ram that operates the lift usually sinks into a shaft as you describe.  These applications are normally done on buildings of only two stories or so.  Another application is the "Holeless" hydraulic lift.  These can be used up to about 44 feet and utilize a telescoping ram.  For other applications of greather heights, different lifts, usually self-contained electric motors, are installed.  The benefit of the 'Holeless" design, other than the elimination of the need for a deep shaft, is the safety of not contaminating ground water from leaking hydraulic fluids...

[finex]

Two possibilities spring to mind:

1) Have you ever seen a telescoping car radio ariel? The hydraulic ram might be in several shorter sections, all fitting inside one another.

2) The "Long steel poles" you describe could actually be the hydraulic cylinder itself. The elevator car could be attached to a piston seated inside the cylinder.

[fly258]

The ram definately wasn't telescopic, it was one complete length, about 50 feet long and 12" in diameter. It seems like an awful lot of extra work during the construction of the building to dig a shaft about 50 feet deep just for a fancy lift. The amount of hydraulic fluid displaced and the size of the pump required must be rather large.

[JackRegan]

What you more than likely saw is what is known as a suspended hydraulic lift.......the hydraulic ram has a wheel on the top and suspension ropes go over this wheel and attach at the lift car and the other end in the lift pit as the ram goes up then the lift travels more than the ram does....you get about 40mm of lift travel for 5mm of ram travel...the poles you probably saw were the suspension ropes.

[fly258]

Jack Regan,

there were  no ropes in sight and the ram definately was a ram and not ropes, it showed all the signs of a hydraulic ram with longitudinal wear marks and marks around the circumference where it stops at each floor. At the base, set in the floor was the top of a huge cylinder with what looked like a large hydraulic hose coming out of it.

[JackRegan]

Hi fly

It must have been a sunken ram then, these are becoming less common as having a one peice ram sunk into the ground is a painstaking and expensive option and as you have seen are mainly used on scenic lifts where everything is on show as it is more pleasing to the eye....telescopic rams are also used but these have a tendency of leaking oil as the more stages used the thinner the oil seals becomes.There are many ways of making lifts go up and down.

[madijay]

Hydraulic elevator systems lift a car using a hydraulic ram, a fluid-driven piston mounted inside a cylinder.
read more:
http://www.transitionsmobility.com/home_elevators_cincinnati.php