Edith Cowan University
School of Engineering
Advanced Mechanical Design
Cherry Picker Drive Wheel Gearbox Design
Due Date: 9:00am 27th May 2016
Project Submission: Hardcopy (and electronic CAD files) with a completed ECU coversheet. Submit to Engineering Office, building 23.
Note: Peer and self-assessment will be considered during marking
Your team’s task is to design a Cherry Picker (see illustration below) drive wheel gearbox that is driven from a specified hydraulic motor (documented below). Your team must design the entire gearbox that will be fastened to the cherry picker chassis and allow attachment of the wheel and hydraulic motor. The complete design will need to include the following:
• Gear sizing
• Bearing specification
• Shaft design
• Gearbox housing design
• Seal specifications
• Fastener size specification
• And any other brackets or fixtures that you require
Identical, yet separate hydraulic motors and gearbox in order to steer the vehicle
Figure 1. Example Squirrel Cherry Picker (www.crendon.com.au)
Note: The two front wheels are driven using independent hydraulic motors (this allows steering), and the gearbox between each hydraulic motor and wheel is your design task
There are identical gearbox and hydraulic motor on each front wheel that are driven independently in order to steer the vehicle (note the single rear wheel is a free-spinning castor wheel). The wheel and hydraulic motor are directly attached to the gearbox and the gearbox then attaches to the vehicle chassis; hence the gearbox is structural because it transfers the vehicle weight from the chassis through to the wheel and also supports the internal gearbox loads. As a result, your gearbox housing must include and allow adequate fastening to the vehicle chassis to support such loads. The client has specified that taper roller bearings are used to support the wheel loads. In addition, the client has requested that there is coaxial alignment between the motor and the wheel for packaging purposes. The cherry picker should be designed to operate as reliably as possible to avoid high costs associated with downtime, whilst maintaining a practical design to avoid unnecessary expenditure.
The cherry picker is designed to operate at orchards where the ground is inclined up to an angle of 15 degrees from horizontal. The spacing between the rows of trees are 5m (up the incline), as illustrated in the diagram below. The orchard ground surface is predominantly gravel, where the coefficient of friction with the tyres is 0.35. Each front wheel of the cherry picker (with driver) supports 365kg and then an additional 25kg when fully laden with fruit. The gearbox should be designed to improve the efficiency of fruit picking, where the cherry picker can negotiate between tree rows in the least amount of time, notably, for safety reasons the cherry picker cannot exceed 10kmh. Along with your gearbox design, the cherry picker manufacturer wishes to know maximum safe gradient the cherry picker can navigate and the orchard owners wish to know how much space is required for the cherry picker to navigate between rows.
Figure 2. Illustration of the orchard layout
The front driven wheels (Figure 3) are 800mm in diameter (rolling diameter) and the mounting incorporates 8x M16 bolt holes on a 300mm PCD that are positioned around a 200mm diameter central through hole, as illustrated below.
Figure 3. Example Squirrel Cherry Picker driven wheel (www.crendon.com.au)
The assignment deliverables for the design are as follows:
1. A complete set of design documents for the assembly:
• A design report that details (15%):
? Product design specification
? Manufacturing details (including processes, off-the-shelf components, required treatments, etc.)
• An analysis report that covers (45%):
? Load calculations (prior to further analysis)
? Strength calculations
? Failure analysis calculations of component(s)/assembly where applicable
? Finite Element Analysis of structural components
• A complete set of manufacturing drawings – fully dimensioned of all parts ready for manufacture (Note: this excludes the motor, gear tooth profiles and bearings) (10%)
• SolidWorks 3D model (or equivalent CAD model that can be opened within SolidWorks) of the complete winch assembly and components. Printed (hardcopy) images of all the components in your design are required along with electronic files of the parts and assemblies (15%)
2. Presentation: An informal 5 minute presentation of your group’s design to the class during the final lecture (5%).
3. Teamwork: Cooperate as an effective team with suitable load sharing (5%)
4. Report: All aspects for a quality report, such as grammar, referencing, presentation, etc. (5%)
Note: The written component (excl. drawings) of the design report should not exceed 10 pages, any content beyond 10 pages will not be considered in the mark. The analysis report should not exceed 30 pages, any content beyond 30 pages will not be considered in the mark.