上海交通大学：《Design and Manufacturing》课程教学资源（作业）02_homework

ME 337 homework-lecture2 Due in class on Sept.25,2014 Course ID: Name: Please use A4 size paper and staple them together. Problem 1: A metering pump was design such that a movable pivot controls the stroke of the crank.The pivot is adjustable to any position through a 90 arc about the center of the crank.When the crankshaft-to-movable-pivot line is perpendicular to the crosshead motion,the stroke is maximum.When it is in line with the crosshead motion,the stroke is minimum.Draw the unscaled kinematic diagram of this linkage.Determine the D.O.F of this linkage -Maximum Stroke Crosshead 3 Slide Block Connecting Rod Yoke Displacement to Change from Maximum to Minimum Stroke Movable Pivot Maximum Stroke Position Minimum Stroke Moving Pivot Minimum Stroke Position Solution: 1

1 ME 337 homework –lecture2 Due in class on Sept. 25, 2014 Course ID: Name: Please use A4 size paper and staple them together. Problem 1: A metering pump was design such that a movable pivot controls the stroke of the crank. The pivot is adjustable to any position through a 90° arc about the center of the crank. When the crankshaft-to-movable-pivot line is perpendicular to the crosshead motion, the stroke is maximum. When it is in line with the crosshead motion, the stroke is minimum. Draw the unscaled kinematic diagram of this linkage. Determine the D.O.F of this linkage. Solution:

Problem 2: Verify the mobility of the mechanisms in following Figures. n2 Planet Gear,3 Connecting Rod Slider Input Crank,1 ©B Output Gear,4 Figl.A gear slider mechanism ving Motion Seat A D Resistance Cylinder Fig2.A rowing-type exercise trainer 2

2 Problem 2: Verify the mobility of the mechanisms in following Figures. Fig1. A gear slider mechanism Fig2. A rowing-type exercise trainer

Co A B Fig3.The step to ramp mechanism for the handicapped Problem3: Many high-performance race cars are equipped with a spoiler system that is located on trunk of the car.Spoilers are necessary to improve the traction of the car in high-speed situations by providing an additional down force to minimize the lift coefficients.Following fig shows a retractable spoiler system that would elevate at approximately 50 miles per hour and retract at 10 mph (a)What task does this design satisfy and why? (b)Draw an unscaled kinematic diagram of the mechanism. (c)Calculate the degree of freedom (d)What type of six bar for this mechanism? 3

3 Fig3. The step to ramp mechanism for the handicapped Problem3: Many high-performance race cars are equipped with a spoiler system that is located on trunk of the car. Spoilers are necessary to improve the traction of the car in high-speed situations by providing an additional down force to minimize the lift coefficients. Following fig shows a retractable spoiler system that would elevate at approximately 50 miles per hour and retract at 10 mph. (a) What task does this design satisfy and why? (b) Draw an unscaled kinematic diagram of the mechanism. (c) Calculate the degree of freedom (d) What type of six bar for this mechanism?

(a)Precision Position 1 (b)Precision Position 2 (Fully Retracted) 20 lbf 3 6 O 5 (c)50%Elevation (d)Precision Position 3 (Fully Elevated) Figure P1.74 Solution: 4

4 Solution: