Senior Design 04-05: Team 13

 

For an in-depth description of how we arrived at this final design, see our final report.

Our final CAD model:

Basic components of our design:

-Base

-A-Frame (front legs)

-Back Legs

-Truss

-Swivel Connection

-Outriggers

-Winch and Grabbers

-Trailer

 

BASE

Our base attaches the crane to the trailer. It consists of two rectangles made of 3-inch channel that are connected together with flatbar. Connecting the two rectagles guarantees proper spacing of the legs. Each rectangle has two pin joint connection points made of channel on which the legs mount.

 

A-FRAME

The A-frame carries the majority of the load one the crane. It must resist bending in all directions, and it does so with the help of angled cross bracing and support plates.

The top of the A-frame holds the pipe that forms the basis for the swivel connection. At the bottom of each leg of the A-frame is a re-enforced hole for a pin joint.

 

 

 

 

 

 

 

BACK LEGS

The back legs are made of channel, and they support the A-frame to keep it standing straight upright. When the load is off the front of the crane, the legs are in tension, and when the load is off the back, the legs are in compression.

 

 

 

 

 

 

 

 

TRUSS

Our truss is 10-feet long, allowing the crane to have enough reach to build rooms with a 20-foot diameter without being moved.

The truss is build out of flat bar and angle iron. The vertical portion, which is about 10-inches tall, is build out of flat bar and gives the crane rigidity for carrying the downward load of a packed tire. The horizontal portion is built out of two long parallel pieces of angle iron connected by flat bar cross bracing. This gives the truss side-to-side rigidity and keeps it from twisting while the crane is being rotated.

Along the bottom of the truss is a roller track that allows an electrically powered winch to roll in and out along the length of the truss. This track is held in place by numerous 3/8-inch carriage bolts running all along the bottom of the truss.

At the back of the truss is a plate with 6 bolt holes. This plate allows the truss to be bolted to the top swivel connection with half-inch bolts.

 

SWIVEL CONNECTION

The swiveling mechanism allows the truss to rotate 360-degrees. It uses numerous components to give it strength and stability:

A: INNER PIPE
The inner pipe fits inside the channel at the top of the A-fram. It provides a mounting point for the large bolt and thrust bearing, both described below. The inner pipe also provides some extra bending resistance to the swivel connection.

B: MIDDLE PIPE
The middle pipe mounts around the outside of the channel at the top of the A-frame. It helps gives the top connection enough bending strength to withstand the large moment placed on it by the loaded truss, and also provides a round surface for the brass bushings to sit on.

C: OUTER PIPE
The outer pipe fits and rotates around the middle pipe. It is what attaches to the truss to the crane with plate that bolts to an identical place found on the truss. The outer pipe has a larger diameter than the middle pipe, allowing room for the radial bushings to be mounted between the two pipes to help allow for the swiveling motion of the truss.

D: CAP
A cap made out of a square 1/4-inch thick plate is welded to the top of the outer pipe. The cap provides a mounting place for the bearing housing and carries the downward load of the truss. A 1-inch diameter hole is drilled in the top of the cap to allow the 1-inch bolt to pass through out the top of the whole swivel assembly.

E: ROUND PLATFORM
The round platform is a custom part made by Dave Ryskamp on the lathe in the metal shop. It gives a surface for the thrust bearing to sit on. It sits snug and secure in the top of the inner pipe. The 1-inch hole running vertically through the middle of the platform allows the 1-inch bolt to pass through.

F: THRUST BEARING
The thrust bearing sits upside down in this assembly, meaning that the casing for the bearing is on top of the bearing rather than on the bottom. The casing, attached to the cap, sits on the bearing, which sits on top of the round platform mounted in the inner pipe. The bearing fits around the 1-inch bolt to secure it from moving side to side.

G: BOLT
The 1-inch diameter bolt runs up through the middle of the whole assembly, and is capped with a nut on top of the cap on the outer cylinder. The bolt helps secure the whole assembly together, and it helps keep the bearing lined up.

H: BRASS BUSHINGS
Two radial bushings made of brass fit between the middle pipe and the outer pipe, allowing the outer pipe to swivel around the middle pipe. The bushings are thin brass rings that are press fit into the inside of the outer pipe, one near the top of the pipe and one at the bottom. Using two of them keeps the swivel assembly lined up vertically. They transfer the bending moment caused by the load on the truss from the outer pipe to the middle pipe. Applying a thin layer of grease to the outer surface of the middle pipe allows for easy rotation of the entire assembly.

OUTRIGGERS

The outriggers are mounted directly to the trailer to help give the crane more stability while it is in use. Using outriggers takes the load off of the suspension of the trailer which will make the whole crane bounce less as it lifts the load.

The outriggers consist of two concentric pipes. The outer pipe is welded to the back of the trailer just behind the rear wheel-well. The inner pipe slides down out of the bottom of the outer pipe and is held at the needed height with a pin that fits through one of the holes milled in the pipe.

 

WINCH AND GRABBERS

The grabber is what actually picks the tires up, and the winch is what pulls them up in the air. The winch was purchased at Harbor Freight tools, and the grabbers were formed out of 7/8" round steel bar.

TRAILER

The trailer on which the prototype is mounted is a double-axle 16’ long x 7’ wide utility trailer with a 1-foot high railing on three sides. It was delivered on February 11th by friends of James Kuiper who were driving a van back to Michigan from New Mexico.

Some modifications were made to the trailer in order to make it more functional for holding the crane:

- In order to bolt the crane easily to the trailer, nut plates were mounted to the bottom of the wood on bed of the trailer. Holes were predrilled to line up with the nuts in these plates. This allows the crane mounting bolts to be removed or installed very quickly by only one person once the base is set in place

- The wooden planks that make the bed of the trailer were bolted down to the frame of the trailer to keep them from bowing up when they are pulled up on by the crane when a load is placed off the front.

-The trailer was painted

 

Here is a picture of our finished crane: