Don't Screw it Up!

Groan....Dad humor.....Anyway....

I had just finished bashing power screws for their inefficiency in a previous article, and I make no apologies for it, but screws definitely have their place in the world of heavy lifting. Because of their inefficiency, they can make a great brake! Perfect for something like a jack.

The jacks need to be very narrow to slip in between surrounding piping and structure. The screws, driven by a small planetary gear box and bent axis motor are extremely compact.

We built as system like the one below last year, this one is slightly smaller. We're lifting a 35 ton heat exchanger. The heat exchanger needs to come up on a 10 degree angle in order to clear the rigid welded piping connected to it (Why no maintenance spools!?).

The system consists of four custom hydraulically driven screw jacks . The drives are mechanically synchronized using a pressure compensating valve - no fancy electronics. I think hydraulic power beats pneumatics hands down for controllability, and can be used in a hazardous environment, unlike off the shelf electric motors. The components are also amazingly inexpensive! You can build a cheap version of these jacks with parts from Tractor Supply.

The bad news: As usual, we have no crane access, so all of the components need to be brought in on pallet jacks and/or carried by my poor co workers. The support structure is all stick built in place and snugged up using tie-rods. We're going to assemble some light weight hoists on walkways above to help with assembly.

Check this out: