# Scissor Jack

Topics: Force, Free body diagram, Problem solving Pages: 3 (710 words) Published: December 17, 2011
Critical Analysis Of Load Distribution On a scissor Jack

Gabriel Chong, Paul Stegner, Chris Yorgey

Department of Physics and Engineering

Elizabethtown College, Elizabethtown, PA
Email: chongg@etown.edu, stegnerp@etown.edu, yorgeyc@etown.edu

INTRODUCTION

In this discussion we will introduce our critical analysis of the load distribution on a scissor jack. It has been specified that this jack is to hold a load of 100 lbs on the top plate, with the jack height set to 7 inches. Our analysis will focus in on the forces experienced by the screw which adjusts the height of the scissor jack. We will solve the problem using general formulas and variables so that our results can be universally applied. With the given information, we will determine the load as it is redistributed from the plates to the legs, and from the legs into the pegs that act as supports. We hypothesize that by solving the generic system for this scissor jack by assuming the weight is evenly distributed, we can gain better knowledge of the interaction of forces on the scissor jack, including the effects of placing the load in different positions.

PROCEDURES

Our main goal as team A.W.E.S.O.M.E. (Always Working Extremely Serious On Momentous Experiments) was to solve the system based on a generic system of equations. We accomplished this task by assuming that the 100 lb force is being evenly distributed on all four pins. Knowing this, we could easily solve the system by viewing the FBD’s in two dimensions. Thus, in order to get the correct value, all we would have to do is multiply our theoretical answer by 2 to include the opposite side of the 2-D diagram. By solving for variables before using any numbers, we simplified our calculations.

RESULTS

We used the fundamental equations below for all our calculations: | |Σ[pic] |(1) | | |[pic] |(2) |...

References: Hibbeler, Statics, Pearson 2007