Help with Hydraulic Catwalk

[Helplz]

I'm trying so save my father a lot of money on a project. What i can't figure out is how the Skate is operated. I've been told an amount of things. But what are all these people using? here are the examples...

http://www.youtube.com/watch?v=J2mioe-x19U

http://www.youtube.com/watch?v=8nT5z11S3iY

http://www.youtube.com/watch?v=qOVESlv8OH4&feature=related

now, the skate is the piece pushing the pipe up... my best guess is that they are using some sort of towline conveyor.... to be honest i'd even be willing to pay someone engineer wise to draw me up some sort of blue print. We build Well service rigs for a living... I'm a very talented welder, with alot of experience in hydraulic raising cylinders, leveling jacks, etc.... but for the life of me i can't figure out what to use to run the skate with hydraulics. I've considered Telescopic Hydraulic cylinders, but the skates in the video seem to operate more smoothly then i image one being used with a scoping cylinder would operate. If someone has any idea whats being used and can send me a link of where to buy one, i'd greatly appreciate it!

 

[MikeHalloran]

The unit featured in the second video seems to have a telescoping cylinder, with various visible pieces attached to different stages.

For a really long stroke, I can think of a few mechanisms that should work. Recognize that I have no inside info about what is actually used, this is just speculation.

- A long roller chain loop, driven by a hydraulic motor at one end. Such a rig could be very compact, and relatively inexpensive. Some of the not so smooth motion seen in the videos could be explained by roller chain slap or whip.

- A super long cable loop, driven by a much shorter linear hydraulic cylinder and a 'motion increaser'. I don't know its formal name if it has one, but it's basically like a block and tackle run backwards; an array of fixed pulleys and an array of movable pulleys, with wire rope laced around all of them, with the hydraulic cylinder changing the center distance between the blocks. Mechanically similar to a carrier's arresting gear engine. The bend radius for the wire rope limits how 'thin' the assembly could be, so I don't think the rigs in the videos are using anything like this. Also, I think you'd need two, opposing each other, to run the skate horizontally.

- A super long leadscrew. It would probably need to be sectional, and it would need intermediate bearings, so the traveling nut would need some fancy mechanism to disengage from one screw section and smoothly engage the next screw section while under load. Probably too complicated for the oil patch.

- A long cable with a multipulley friction drive at one end, not unlike a ski lift. Bend radius says no.

- A linear electric motor with a fairly simple traveler on a fairly simple rail. Only money limits how long you can make these, and you can get some really strong ones today.



Mike Halloran
Pembroke Pines, FL, USA

 

[potteryshard]

Hydraulic motor on carriage with attached pinion which engages rack welded to structure? Rack can easily be assembled from short pieces of prefabricated rack section. Hoses to motor carried on festoon trolleys.

 

[hydtools]

I would say it is Mike's first guess, roller chain loop driven by a hydraulic motor. Easy, simple, durable. The jerkiness is probably the operator starting and stopping the skate under misdirection for the video.

Ted

 

[dvd]

I would go with the roller chain also. Considerations for a chain are take-up: the chain is going to stretch with wear; this is a reversing drive; there will be some thermal growth of the chain. You should get some engineering help on this. (Maybe your local Motion Industries, IBT, or some other power transmission component supplier, can let you know who they sell lots of this type of equipment to as a lead for a possible LOCAL engineering source.) By time you re-invent this gizmo you may have some painful lessons learned and more costs than anticipated. If you don't have a spec developed to engineer from you are going to have no recourse if there are problems.

As for the jerkiness exhibited in the videos, I would suspect PLC and control delays....

 

[potteryshard]

The video seems to show two different motions; first the whole track assembly tongues out one ram's worth. When that cycle ends, the chain drive seems to start.

 

[TenPenny]

I would venture a loop of wire rope / chain - exactly the same as a typical garage door opener.

 

[dukecat]

I agree, you are definitely reinventing the wheel here. There are plenty of pitfalls that have already been ironed out by experienced builders and you will save yourself a lot of headaches if you purchase an off the shelf unit. If you can't figure out how the Skate works, you aren't going to be able to figure out some of the more challenging aspects of catwalk manufacture.
Google "Hydraulic Catwalk" to find some of the bigger builders!

 

[Bossmech]

We build one of these on a gooseneck trailer. Use a hydraulic motor with #80 chain to power the skate. The chute is powered via a hydraulic cylinder for shorter applications and a chain drive system for the longer chute. The lift is a dual power up/power down cylinders.

 

[IceStationZebra]

If you look at this video I believe you can see the chain. ISZ

http://www.youtube.com/watch?v=uOwujkJ-3tE&feature=related