final version

Personal Track Vehicle

ENGELBERT DIEC ASHLIE REOTT

STEVEN MONTEVIDEO LAWRENCE YANG

Overview Responsibilities Break Down Design Requirements Motor and Battery Shaft Coupler Bearings Differential Braking/Steering Shafts Cost Analysis Future Design Considerations

Responsibilities Break DownEngelbert Diec Ashlie Reott

● Motor● Battery● Performance

Analysis● Rear Axle Shafts

● Shaft Coupler● Bearings● Drive Shaft

Steven Montevideo Lawrence Yang

● Differential ● Brakes● Solidworks assembly

All

● System requirements● Initial design● Solidworks drawings

Design RequirementsCustomer Requirements Engineering Requirements

● Safety

● Easy to use

● Reliable

● Capable

● Adaptable

● Affordable

● Concealed power train; 5 point harness; roll cage; 2 kill switches

● Only two user inputs; minimum age: 16 years

● Lasts at least 5 years (8 hr/wk)

● Climbs 15 degree incline; overcomes 6 in. high obstacle; water/splash resistant

● Traverses concrete, dirt, gravel, sand, slight mud; forward and stop capability (no reverse)

● Costs less than $15 000

Additional Specifications

● Two driven tracks● Size: 4 ft. wide, 6 ft. tall, 7 ft. long● Max payload: 250 lb● Weight of entire vehicle: 400 lb● Maximum speed: 30 mph at 0 degree incline● Maximum speed: 15 mph at 15 degree incline● Stopping distance at max speed: 50 ft

Motor and Battery - Selection

● Minimum power to tracks: 10.2 hp● Minimum motor power output: 12.7 hp● Efficiency: 78%● Current: 116A● Battery: 48V 300Ah

Motor and Battery - Performance● Motor output power: 13.0 hp● Actual power to tracks: 10.4 hp● Minimum battery life: 1 hr 50 min● 0-30 mph (flat): 5.8 sec● 0-15 mph (inclined): 30 sec

Drivetrain Design Alternatives

Differential• Motor to Carrier 1:1

• Pitch Diameter = 7.5 in• Spur Gears

• Spider to Bevel 1:1• Pitch Diameter = 2.5 in

AGMA Gear Stresses and Strengths

Gear Material: Through-Hardened Steel w/ Hb = 350

Spur Gears Bevel Gears

Bending Stress

11.25kpsi

Contact Stress

62.2kpsi

Bending Stress

12.5 kpsi

Contact Stress

117.4 kpsi

SF 4.52 SF 2.38 SF 1.65 SF 1.31

Shaft Coupler

● “Lovejoy Coupling”● Replaceable center● Iron hubs● Hytrel spider● Max speed: 3600 rpm● Max torque: 790 inlb● Max angular misalignment: 0.5º

Coupling Hub

Spider

Bearings

● High-load steel ball bearings● Material: steel● Double shielded● Max speed: 5000 rpm● Max load: 3864 lb

Braking● Total Torque: 3485.81 lbf*in● Rotor Diameter: 8 in● Brake Pad Material: Sintered Metal

○ COF: 0.33● Brake Pad Inner Radius: 2.75 in● Brake Pad Outer Radius: 3.80 in● Pad Angle Displacement: 50°● Minimum braking distance: 33.4 ft

Steering● Hydraulic Brake Pedals● User Controlled Limited Slip “Differential”

Shaft Design - Rear Axles● Factor of safety: 1.5● Material: AISI 1040 Q&T (86 kpsi)● 1.25” - 1.375” diameter● Differential and track wheel attached by key● Bearings located by shoulder and housing

Shaft Design - Drive Shaft● Material: AISI 1040 Q&T (156 kpsi ultimate strength)● 1.00” - 1.25” diameter● Shaft coupler and gear attached by key● Bearings and gear located by shoulder and housing

Cost AnalysisPart Quantity Price

Transwarp 7 Motor 1 $1,700.00

12V Lead Acid Battery 4 $648.00

7.5" 12 pitch spur gear 1 $80.00

7.5" 12 pitch gear w/ carrier 1 $130.00

2.5" 10 pitch spider gears 2 $120.00

2.5" 10 pitch bevel gears 2 $120.00

200 mm wave disc brake rotor 2 $90.00

EBC sintered brake pad 2 $70.00

Shaft Coupler 1 $15.00

Custom Motor Shaft 1 $15.00

Custom Half Shafts 2 $40.00

Spider Shaft 1 $5.00

Spider Shaft Fitting 1 $2.00

1-1/8" ID Double Shielded Ball Bearing 1 $27.87

7/8" ID Double Shielded Ball Bearing 1 $15.85

1-1/4" ID Double Shielded Ball Bearing 4 $111.48

1/2" ID Steel Ball Bearing 2 $15.30

2-1/4" ID Steel Ball Bearing 2 $60.00

Total $3266

Future Design Considerations

● Integrating our drive train design into the whole system

● Investigate more cost-effective options

● Relocate rear axle bearing to better distribute loads

● Larger brake pads for minimal servicing

● Helical Gears on differential instead of spur gears

● Reduce system weight