Hardware of Powerchair Football

1. Premises of Powerchair Design

• Competition-specific machines are not intended for daily use
• Outdoor driving with rear casters lowered carries damage risk
• Drive Profile 5 is configured exclusively for competition

→ Competition chairs assume high output and rapid acceleration/deceleration
→ Tire philosophy differs from standard medical power wheelchairs

2. Leading Platform: Strike Force Structural Notes

From US Patent 8,678,114

US8678114

Structural elements
• Low center-of-gravity design
• Forward-extended guard
• Wheel guard surrounding drive wheels
• Rear caster support limited to within 10 inches behind the drive axle

Patent statement
“The rear edge of the seat is less than 10 inches behind the drive wheel axle.”

US8678114

Design intent
• Reduction of G-forces
• Spin stability
• Suppression of rear overhang

→ Tires assume sharp turning conditions
→ Lateral load dominant

3. Vehicle Specification Summary

• Drive wheels: medium diameter
• Front wheels: small casters
• Rear wheels: anti-tip casters
• Battery: 24V gel type

Sudden stops, rapid turns, lateral sliding
Wear mode dominated by uneven wear

4. Tire Size

3.00-4

Industrial cart standard
Outer diameter approx. 260 mm
Rim diameter 4 inches

Estimated reasons for adoption
• Availability
• Load capacity
• Standardization in competition chairs

5. Difference Between Solid and Pneumatic

Solid

• No puncture
• Minimal deformation
• High lateral stiffness
• Low rebound
• Consistent wear progression

Competition suitability
Stable
Linear response
Low shock absorption

Pneumatic

• Large contact patch deformation
• Shock absorption
• Lateral deflection occurs
• Requires air pressure management

Competition suitability
Possible influence on ball control
Potential delay under lateral load

6. Regulatory Constraints

FIPFA guard dimensions are fixed

Strike Force User Manual 2018

→ Limited room for changing tire outer diameter

Seat height
Axle position
Rear overhang limitation (patent)

→ Changing tire diameter directly affects vehicle stability

7. Tire Design Considerations

Competition-dominant factors

• Lateral load
• Spin wear
• Indoor flat floor surface
• Relatively constant surface μ

Required properties

• Low rolling resistance is secondary
• Lateral stiffness
• Wear resistance
• Heat resistance

Distinct from general automotive tire design philosophy

8. Relation to the Patent

The patent focuses on frame, guard, and center-of-gravity positioning.

US8678114

Material composition of the tire itself is not specifically restricted.

→ Room exists for tire improvement
→ Area for material differentiation

9. Summary Notes

• 3.00-4 is an industrial standard
• Solid tires tend to dominate
• Stiffness compatible with low center-of-gravity design is required
• Wear dominated by lateral sliding
• Tires are still largely off-the-shelf industrial products

Material research potential exists
Especially in lateral stiffness control and reduction of wear particle generation

Sources

Strike Force User Manual 2018
US Patent 8,678,114