A dairy farmer in Bellows Falls Vermont has asked us to design a small, gasoline-engine powered winch-hoist to use for the lifting of hay bales into the barn loft. A preliminary design concept is shown in the accompanying figure. A single-cylinder, two-stroke engine with flywheel is coupled to a gearset to reduce the engine speed and boost its torque appropriately. The best ratio for this gearset is yet to be determined. The jackshaft drives one side of a clutch, which passes the torque through to the winch drum. The drum shaft has a brake to ground. The drum is wound with steel wire rope which has a forged hook at its end. The entire winch assembly will ultimately be mounted in the hayloft above a central hatch. Hay bales will be manually attached below and manually removed above. See Figure 8-4 in text.

    Throughout the term we will design various parts of this assembly. There are many elements to this relatively simple machine. We will only have time to address a small fraction of the total collection of parts. Some of the elements which need our careful design attention are:

• the wire rope

• the hook

• the shaft

• the shaft bearings

• the gearset

• the keyed coupling

• the cylinder headbolts

• the clutch springs

    We will find that the designing of these parts is interdependent. Changes to one element may reflect through the system and require compensating changes in other parts. We will address the design of various parts as we develop and discuss the necessary theoretical aspects of the course topics.

    Some of the force analysis can be done with the program ENGINE supplied. Other analysis can best be done using a program such as TKSolver or MathCad, or with just a spreadsheet.

    We will attack this design project in six (6) phases as defined below. Each phase will be allowed one week of effort beginning in week 2 of the course. This will ultimately be a group project, but until the groups are formed (at phase 2) you will each work independently on phase 1 and then combine your efforts on the later phases.

    Five weekly progress reports will be required in a format defined in the Progress Report Specifications handout supplied. A final Project Report will also be expected whose format will adhere to the separate Project Report Specifications handout supplied.