Team Rock On Final Presentation

ME 4182Submitted 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 2nd 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:

3

32

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MMAX

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Engineering Analysis

• Tension – Scenario 1

• Initially, the tension in the wire is 41.25lb

• Tension – Scenario 2

• Rock mover remains stationary and rock slides onto forks

• Coefficient of friction for sliding on metal forks is 0.3

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!

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?