Term Project (teams of 2 students max.)
Progress report Due April 1st
Final report due May 1st
The Man Lift
Background: Some jobs require a person to be lifted to heights of 40 feet (or 12 m) to perform a variety of tasks (servicing public lighting poles, work on exterior of buildings, tree cutting etc.) These tasks require a “manlift” similar to the ones shown in the pictures below. There are several types of these pieces of equipment available in the market. A typical worker can weight up to 240 lb and carry up to 60 lb of tools.
Social Context: Many accidents occur due to lack of stability within the range of motion of the crane. Obviously, safety is the number one concern in the design of a manlift. But if the crane is over-designed, the crane will not succeed in the market do to “overkill” design. But some standards are available from OSHA and NIOSH to use as guidelines. You are required to reference OSHA and NIOSH guidelines on manlifts.
The Device: An articulated two-arm manlift is to be designed to be mounted on a pickup truck (example Ford-450) to reach a height of 40 ft. The lift will be capable of carrying a 240 lb person with up to 60 lb of tools. The actuators are to be commercially available hydraulic cylinders, which need to be designed (selected) according to the application. The two arms when fully retracted must fit within the moving frame of the pickup truck. See illustration provided.
The Mechanism Design: You are asked to design mechanisms of appropriate size and shape to be part of the manlift system, including the hydraulic actuators and the sizes and dimensions of the links needed to produce the lift motion. The materials to be used should all be commercial steel.
P.E. Code of Ethics Essay: You are required to find the P.E. Code of Ethics on the internet (http://www.mtengineers.org/pd/NSPECodeofEthics.pdf), read it and include a brief essay on the “Professional Responsibility” of designing a manlift as in this project and its manual of operation and service.
Defining the Motion:
The lifting motion will be produced by two actuators, which can move simultaneously or independently with individual separate controls. The range of motion should be such that the truck will NOT topple under the lifted weight at the maximum extension.
You are expected to write a report on the design process with the following elements in it:
1. Front page with title of project, names of students, class section and date.
2. Introduction; brief narrative of your design objectives.
3. Background; Description of the mechanism used for the lift including the use of 4 bar mechanisms or 6-link mechanisms (a 4-bar with an actuator attached to a link).
4. Design description of mechanisms to yield the lifting motion range of 40 ft or 12 m height. (Choose one height with its unit system; metric or English).
5. Detailed engineering drawings of the mechanisms with dimensions
6. Essay on the NSPE Code of Ethics.
7. Illustrations of the mechanisms in various phases of motion
8. Analysis of velocities, accelerations and forces through the motion.
9. Engineering Conclusions (very important)
It is expected that you will use Working Model and at least another program from the text CD, to document your project. You may also use Matlab for your calculations.
A progress report with 50% of the total material approximately is due on April 1 (Mechanism synthesis, motion analysis and commercial cylinder selection). This report should have at least points 1 through 6 as close to final form as possible (Point 6 is a Must in the Progress Report). This report will count as a regular assignment in class.
Manlift on a pickup truck Extended (assume only plane motion in X-Y)
Manlift on a pickup truck Retracted