Suspension

The current focus of the team at this moment is the suspension. The importance of the suspension is high, the team must establish a design that allow the user of the mushing cart to maneuver the vehicle safely from a rear position while all the pivoting wheels are located on the front of the cart.

After searching for ideas, the team was able to find an off-road handcycle used for extreme sports by the handicap.

Inspired by the design, the team hope to use this for their mushing cart with steering being possible from a rear position. 

Solid modeling has begun on the suspension system, and the team hopes to have those completed in the near future.

Updated WBS

Decision Making

Over the Spring break, the team met to make further decisions on the urban mushing cart. The following are possible options that we have narrowed down for the use of our chassis.

• Square vs. Round Tubing
• Thickness of material
• 4130 Alloy Steel (Chromoly) vs. 606-T6 Aluminum

Pros:

• Easier to weld

Cons:

• Load concentration areas

Pros:

• Cheap
• Widely Available

Cons:

• Harder to weld/bend

Future tasks

• Budget
• The team also spoke about funding for the cost of the material. The budget is currently $1000, but in the case that budget will be exceeded the team has determine that fundraising will be a necessity. The team has contacted fundraising coordinators at Warner Brothers Studios to attend TV show tapings in the event that more funds are needed.
  
• CAD
• A few things that the team will be working on in the following weeks is create rough CAD designs in order to get an idea of what materials will be more advantages. This task will also assist in determining what material and shape we should use when our CAD designs undergo static analysis. 

Finalizing the Design

The team set limits for components in order to prepare for narrowing the options of components in an attempt to finalize the design. Below is what the team established:

=

where,

1. Tires
2. Length of frame
3. Double barrel lever disk brakes
4. Height of frame
5. Steering
6. Suspension 
7. Digger brake
8. Hitch

The Decisions that were made were made the week of the (3/18/13) were:

• Tires
• Buy
• Size: 12-16 inches (in diameter)
• Frame (length & height)
• Build frame
• 6ft. x 3.5ft. x 3ft.(L x W x H) in approximation
• Brakes
• Buy
• Double barrel lever (disk brakes)
• On all four wheels
• Steering
• Make handlebars
• Buy handlebar grips
• Front steering
• Suspension
• Buying
• Front suspension
• Digger Brake
• Make
• Hitch
• Make
• Hook to carabiner

To be determine in the Following weeks:

With certain areas of the design still in a grey area, the team will work together to fully complete the design by establishing how the suspension will work together with the steering. The steering will also be looking into, currently the idea is to create a four-bar linkage that connect from the back to the front, in order to steer from the back. Finally the team will also finalize whether the cart will have both front and back suspension or just front suspension.

Urban Mushing Cart Visits The Team

The team gathered on campus to examine the client's own mushing cart to gather information and ideas on how to improve on their design.

Google Drive

https://drive.google.com/?tab=mo&authuser=0#my-drive

PDS

Attribute	Type	Metric/Requirement	Unit	Notes
Safe	Objective	# of ways to cause bodily harm
Resilliance	Objective	Varying impact and Temp.	Force/Temp.
Low-Cost	Objective	less than $1000	Dollars
Low-Weight	Objective	less then 85lb	Pounds
User Friendly	Objective	Ease of transport
Regulate Speed	Function	Accelerate as fast as dogs/80% efficiency
Regualte Direction	Function	Change alignment within 5 secods	Time
Decrease Speed	Function	Decelerate from 30-0MPH	MPH
		Stopping must range from 50-100ft	Feet
Stabalize Driver	Function	Reaction force must be less than 2/3 of impact force	lbf
Secure Passenger	Function	Hold lateral force of 500lbf	lbf
Attach Dogs	Function	Sustain tensile forces of 250lbf/dog	lbf
Transfer Energy	Function	Transer Kinetic Energy of at least 25%
Absorb Impact	Function	absorb 60lbf of impact	lbf
Prevent Damage	Function	Components must hold 60% of yield strength