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Design Concept: Specifications

Engine

Briggs & Stratton 31hp Vanguard V-twin

Transaxle

Midwest Super Cub 3 Forward & 1 Reverse Gear

Steering

Hydraulic Steering 2.75 Turns Lock to Lock

Capacities

Fuel Tank - 5.5 Quarts
Engine Oil - 2.3L w/ Filter
Hydraulic Oil - .5 Quart

Dimensions

72” Wheel base
95” OAL
42” Max Width
COG 23” Forward of Rear Axle

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Target Customer

Small family farm owner

Needs	Features
Multi-use	Designed with space for adding implements
Easy to maintain	Adequate space to access and service drivetrain components
Durable	Aluminum in previous models was replaced with steel
Maneuverable	Greater steering radius and new steering brakes

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Market Position

Low end market position

Requirements: production and cost efficiency

Theory of Constraints

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Product Cost: Manufacturing, Cost, and Process Design Combined Strategy

Manufacturing Strategy: Selected Lean Concepts

Prepare organized workstations

Identify and eliminate select applicable lean wastes

System Strategy: Optimal combination of material, design, and process

Aluminum for the front axle and parallel shaft gearbox

Simple Design

CNC machining process

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Product Cost: Workflow Analysis

1. Maximizing Customer Value

Customer Value Added Analysis

2. Cost Efficiency

Theory of Constraints

Benefits of Workflow Analysis

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Tractor Cost Overview

* = shown as a percentage of total manufacturing cost

Profit margin	20%
Total Manufacturing Cost / Unit	$13,546.17
Manufacturing Variable Cost	$11,779.28
*Indirect Manufacturing Cost	10%
*Research and Development Cost	5%
Suggested sales price	$16,255.00

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Decision Process for Design Details: Operator’s Station

Design decision I: Steering column material

Design decision II: Frame length

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Decision Process: Steering System Design

Steering System Options

Selected:

Hydraulic system

Alternatives:

Rack and Pinion

Electric

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Design Details: Drivetrain Design

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Design Verification: Brakes

Brake Design Version I

Internal brake built into the transaxle

Testing

6’ moment arm on axle shafts

Brake Design Version II

Disk brakes on both rear wheels

Disk Brakes

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FMEA – Electric Kill Switch

Bolt connection failure

Lock nut

Loss of battery power

Warning message on operator’s display

Wiring failure on switch end or battery end

Final quality control test before shipping

Internal switch failure

Switch is tested 10 times before installation

Switch failure due to contaminants

Operator’s manual reminder to check the pin for contaminants after each oil change

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Risk Identification, Assessment, and Resolution �

Clutch Hydraulic Throwout Cylinder Evolution and Re-Design

Hydraulic Throwout Cylinders

Pre-fabricated throwout cylinder

Polybuilt designed cylinder V.1

Risk Assessment

Polybuilt designed cylinder V.II

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User Safety

Pressure switches on the brakes

Gear position sensor

One breakaway switch and 1 kill switch

Heat shielding improvements

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Product Liability Assessment

Operator Safety Requirements Met:

1. Back of seat does not reach past the back of the rear tires

2. Maximum seat width of 20” and depth of 22” were not exceeded

3. Maximum backrest height of 12” was not exceeded

4. Shafts in the drivetrain are made of steel and contain safety loops

Remaining Area of Potential Risk: Roll-over

Proposed Corrective Action: Development and testing of bars

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Polybuilt Company Organization, Team, Product, and Process Planning

Organization Structure – Matrix

Level of specialization – 3 focuses for product development

Advantages of cross functional product subsystem development teams �