Team Rock On Final Presentation ME 4182 Submitted 7/25/06 Yuki Miyasaka, Anthony Palladino, David Price, Whitney Price, Ricky Sandhu

The Problem Landscaping is a common enjoyment among homeowners. Heavy boulders are very common on property; however, almost impossible to move. If one wants to move a heavy rock, they have 2 choices: 1. Use brute force and risk hurting themselves. 2. Rent a bobcat, figure out how to get it home, tear up the grass moving it, etc. Neither option is very easy or practical.

The Goal Create a cart capable of loading and unloading a large rock, and relocating it to different places within the yard. It would be designed to accommodate up to a 300 lb rock. Our idea would be marketed to the average homeowner with landscape needs. The individual could either rent or buy this device and easily store it in a garage or shed when not in use.

Original Design

Peer Input Q: Why does the device not incorporate a wheel barrel or attach to a wheel barrel? A: It is not sturdy enough and requires too high of a user input ;roughly 40-60% of total weight. Q: What about the vast variety of rocks? A: Redesigned strap system provides greater stability, a rock w/ a diameter ≥13” will work with the device. Q: What if the rock is underground? A: It doesn’t matter because the spikes dig underneath. If the rock severely buried, shoveling around it will be required. Q: Any specific design concerns? A: To reduce friction on the wires, a sleeve bearing was incorporated into the design.

Changes Made to the Design Ratchet system moved higher for ergonomic purposes Sleeve bearing added to reduce friction on wire while pulling the load Step plate added to help leverage Strap system redesigned to be more adjustable A 2 nd ratchet added to ensure better loading Finer details investigated such as materials and dimensions

The Final Design

Solid Round Shaft Safety Factor static loading: Yield Strength Structural Steel ASTM 36 =58,000psi Using Safety Factor of 3 Bending Moment = 1500 lb-in Minimum diameter = 0.92 in Bending Moment of Prongs: Engineering Analysis

Tension – Scenario 1 Initially, the tension in the wire is 41.25lb

The Final Design The device consists of 5 subsystems: –Frame –Ratchets –Strap system –Wheels/axle –Pulley system

The Frame The frame is 48” tall and is made out of structural steel of 1 ¼” diameter and 1/8” thickness All connections to the frame are welds

The Ratchet Subsystem Consists of two ratchets. The ratchets used are rated 2 ton. They were linked together to allow only one ratcheting action; however, they are now separate Bolted to plate which is welded to the frame Connects to strap subsystem

The Strap Subsystem Made of polypropylene Has 2 sets of hooks to attach ratchet system to accommodate different diameters Hooks placed at 18” and 30”

Wheel/Axle Subsystem Consists of 2 all terrain wheels 12” diameter Steel axle

The Pulley Subsystem Consists of a rod within a tube Tube is welded to cart Rod rotates to redirect tension Redesigned from traditional pulley system

The Prototype

Demonstration The Rock Mover in Action!Action

Design/Prototype Differences Design Pulley System D shaped handle Ratchets interlocking Step plate or Hinge bar 1” round spikes Polypropylene Strap system Prototype Sleeve Bearing Bar handle No connecting bar No Step plate or Hinge bar ¾” hexagonal Chisels Wires used as strap

Future Improvements Wheel selection Remove step plate or allow it to fold out of the way for certain slopes of terrain Increase height of cart to increase leverage Refine the pulley system as the current design and prototype design are flawed Check for over engineering

Questions?