Long-Stroke Rodless Hydraulic Cylinder 1

[USMechE6]

Hello All,

I'm looking to replace vertical lift of ours that utilizes a chain-over-roller hydraulic cylinder, with a 93" stroke that carries a drum (and conveyor) up about 163". I would like to use our current hydraulic system (for various reasons) so I am considering moving to a rodless cylinder. I haven't had much success locating a manufacturer of rodless hydraulic cylinders with this stroke (let alone specifying bore, load capacities, etc. yet). Does anyone know if someone makes something like this? I can quickly tell it's not an industry standard. I'm also open to other ideas. Electric is possible but would require a complete overhaul of the system the lift is apart of (changing obsolete PLC, drives, motors, etc.). This should all be done anyway but isn't something we can necessarily tackle right now.

 

[hydtools]

Maybe a hydraulic motor instead of a cylinder.

Ted

 

[USMechE6]

Interesting idea. I could use that to power a screw system, or a rack and pinion. I'm imagining the former due to vertical space constraints. Any idea on the speed, smoothness and drift associated with something like that? It would need to hold the conveyor in place sometimes indefinitely.

 

[MikeHalloran]

Star for hydtools; a hydraulic motor makes enormous sense here.

If there's a static load/torque on it, and you want it to maintain position indefinitely, you'll need shear-seal or soft-seat blocking valves to prevent rotation of the output shaft, or a friction brake to immobilize it mechanically. The right servovalve will hold position for as long as the power is on.

The cheapest way to get vertical linear motion from a hydraulic motor is sprockets on a horizontal shaft, and roller chain.
You don't need a brake to hold position if you use a leadscrew with a fine-ish pitch.



Mike Halloran
Pembroke Pines, FL, USA

 

[hydtools]

Depending on the speed you need, a worm drive gear box would be self-locking and indefinitely hold the load.

Ted

 

[USMechE6]

Thank you both for the info. In addition to investigating that option, what do you think of Greenco's TracTrol cylinders? (Page 18) Link

My specific loading requirements would probably require either more than one or an extended trolley, both of which their engineer said could be done. I would think the latter so that I'm not worrying about delivering the same flow to each. Anyone have any thoughts or experience with these? I've only used their smaller, pneumatic versions in horizontal applications. I'm not sure what kind of drift performance they have or longevity.

 

[MikeHalloran]

I'd be nervous about using those cable cylinders in a hydraulic system.


Mike Halloran
Pembroke Pines, FL, USA

 

[hydtools]

I do not see how a good hydraulic seal can be had on the cable entering and exiting the cylinder.

Drift depends on reliability of the piston seal as well as valves.

Hydraulic motor, worm drive, roller chain, done.

Ted

 

[USMechE6]

I see what you mean. For the hydraulic motor and chain design, are you envisioning one sprocket at the bottom and one at the top with one closed chain around them? Our current lift utilizes two chains, which I think can just lead to slightly uneven loading and racking.

 

[hydtools]

A picture or two of your current system would be helpful.

Maybe a chain loop. Maybe a pull-pull chain somewhat like a rack and pinion. Double sprocket pull-pull. Just imagination and creativity to do what you want to do.

Ted

 

[BUGGAR]

Yes, a picture and the loads would help. I can recommend a GM electric-on-hydraulic convertible top drive mechanism which will meet your stroke but I need your loads. It's programmable too. Everything on a car is.

 

[USMechE6]

My apologies for the long delay, I was out on vacation. I hope you've all had good holidays.

Due to I.P. restrictions I can't show a picture of the set-up in the field, but it's using a Langely EH-102 Stationary Powerlift. Link
There is a single hydraulic cylinder that lifts a plate with two sprockets on either side, which chains wrap around and down to the carriage that is raised. This configuration doubles the displacement of the carriage with respect to the actuation of the cylinder.

The current load is about 300 lbs. (conveyor + drum), with the C.O.G. about 10" offset from the axis of the cylinder and elevator frame that the carriage's rollers ride in.

 

[hydtools]

They show cable driven models as an alternative to hydraulic cylinder models. Another option for you. Maybe substitute a hydraulic motor for the electric to drive the cable drum.

Ted