Making of an "A" framed adjustable height rolling gantry crane

[Brucker]

The shop has been in need of a more graceful way of handling heavy objects then just our forklift. The shop is small and the scheduled is always packed, so shop space is limited, usually leading to having to move a bunch of equipment and various projects around in order to make room for forklift to maneuver. This eats up a lot of time and energy. Been also missing having an overhead hoist like the old shop had. It made loading the plasma table effortless. And with the new plasma table on the schedule to be finished up this year, as well as a couple vehicle body swaps, figured a solution should be found sooner than later.


Having looked at a lot of commercially available options and the price tags associated, nothing quite fit the bill. Decided to design and build exactly what was needed in house, rather than paying a pretty penny for something that wouldn't fit the needs perfectly without modification.


The crane needs to be capable of lifting and moving at least 1 ton (2000 pounds) of weight. But would like to build in a safety factor of at least twice the desired lifting capacity (so 2 ton overall capacity) to insure it will always be safe to use around the shop without pushing its limits. It will need at least one set powered hoists and trolleys. It needs be able to roll easily around the shop, but also stay locked into a certain position when called for. "A" framed sides would allow for the most clearance and maximum amount center leg length opposed to an upside down "T" or triangle side. So 4 high capacity swivel casters with brakes will be needed. But anyone who has tried to push around a heavy object on 4 swivel casters knows it can be a pain to keep tracking in the correct orientation. So swivel locks will be needed as well to aid in that process.


It will need to be wide enough to span the plasma table the short way (about 6' wide) while still being able to access the floor beside it for the loading and unloading of materials (up to 5' wide). It also needs to be able to lift a vehicle body off of it's chassis, move it next to the chassis, and be lowered down onto stands. Though it needs to be narrow enough to fit the long way through the shop's big overhead door (15.5' wide). And ideally as narrow as possible to save valuable space. So a 14' span between the legs and just over 14.5' overall width was chosen. The height was fairly straight forward. It needs to be able to fit out the lowest overhead shop door, and then extend to as how as the legs would allow. The lowest door is 94" tall so about 93.5" will be the shortest and there should be about 60" of total adjustment meaning the tallest would be about 153.5", or just over 12.5'. Given our highest ceiling is 12', this should work nicely.


After running the numbers for the I beam, a design was quickly sketched up and a materials and cut lists were made and parts were ordered. I beam and the other materials were then cut to length on the swivel mast bandsaw and cleaned up with a flap disc on an angle grinder. Then the small parts were drilled and tapped as needed.










Short video of the caster plates being tapped with the old FlexArm tapping arm:

[Brucker]

The casters and locks arrived. Same setup we use with the majority of heavy equipment we build and use around the shop. Casters are a HD 8"x2" greaseable swivel plate caster with brakes.





And the swivel locks are a simple unit that can be engaged and disengaged by hand or foot. They are able to lock each caster into 1 of four positions or allows the caster to swivel freely.













Assembled together onto the mounting plates

[Brucker]

Then welded together the small parts that will make up the sides or "A" of the gantry frame:

[Brucker]

Started welding those finished parts together to create larger sub assemblies:







And taking those larger assemblies and welding them together to form the sides of the crane:

[Brucker]

Once the sides were almost welded together completely, it was noticed their overall width was going to end up WAY too wide.



So made the decision to add a bend to each leg of each side to narrow the overall profile. Taking the width from about 7.5-8' wide to about 5'. Like this:



Yes, this would lessen the stability some, but not enough to matter much at the heights this will see.


The legs were cut, mitered, and welded back together with only minimal scrap.







Added a gusset along the inside miter joint





welded and sanded smooth:







The scrap from the change

[Brucker]

Welded together the pieces to complete the sides









Must have welded them together fairly square and balanced as they stand on their own very well.





Closer look at the pin plate



Closer look at the hook minders at he bottom of each side. These will be used to keep the hooks and chain/cables in place without swinging when not in use.

[Brucker]

Next up are the legs for the I beam. These will slide within the sides that were just made. Instead of using regular square tubing, I opt to use 2 lengths of rectangular tubing that when welded together to form square beams. This will provide more strength and support throughout the middle of the tubing instead of just at the edges. Also added some round tubing to help relieve some pressure off the shear points and act as guides for the pins for easy alignment.

Drilled the holes in the rectangular tubing, then mated them together and added the round tubing into the thru holes. Welded everything together, then countersunk/beveled the adjustment holes.















Test fit the legs into the sides with the pins

[Brucker]

Time to focus on the I beam itself.



Start by capping the ends.







Then add a couple lengths of angle iron to the top. This will not only stiffen and strengthen the I beam, but will act as tracks for the future power cord management system.

[Brucker]

Some gussets were added in the webbing, to add strength and stability to the beam, and that will also act as hard stops for the trolleys.





Then welded it all up solid

[Brucker]

Attached the legs to the I beam along with a tubular gusset. The end caps of the I beam also tie into the legs.

[Brucker]

Cut a couple name plaques to spruce the assembly up a bit:











Laid out the plaques on the I beam and drill the mounting holes.





These will look good, especially with stainless hardware

[Brucker]

With the main structures complete, it gets assembled. The sides get casters and locks:














And the I beam is placed into the sides and pined into position.

[Brucker]

Name plaques and stainless hardware looking







Added the first manual trolley and chainfall:



Then the first powered trolley and hoist:





Still have to complete the power cord management system, but until then, an extension cord was run for testing. Figured the most dense object that could be found in the shop should be used for the first test. So let's see if it can handle lifting me. And yes, this definitely isn't OSHA approved or even safe. I should have had my safety glasses on... So graceful...

[Brucker]

Time for the real test of the new shop built, adjustable height rolling gantry crane. Using one of the new trolleys and hoists, we lift from the center of the gantry which is it's weakest point. Lifting our main fab table which is just over 1300 pounds completely unloaded. Currently it holds about 600-700 pounds of fixturing, jigs, tooling, clamps, etc. So the table is just under the 2000 pound (1 ton) mark. Once the table is off the ground suspended from the center of the gantry, it is easy to see there is no deflection or distortion of the crane.



The heavy load is easily handled by the new setup. Success!

Just need to fabricate the cord management system and it will be fully complete