Car Jack Mast Design Update. Presented by Doug Eddy and Dr. Sundar Krishnamurty at UMass Amherst for Hoppe Tool on 7/16/10. Control of Scissors’ Motion. This mechanism is under constrained. Potential Remedy.
Presented by Doug Eddy and Dr. Sundar Krishnamurty at UMass Amherst for Hoppe Tool on 7/16/10
This mechanism is under constrained.
Connecting links needed
between center pivots
How well will the 3
sides move together and
keep top in line with
The screw is horizontal
and moves up and
down during lifting.
The shape is rectangular.
Parallel scissors are
rigidly connected at outer
pivots. Legs are made of
rectangular tubing for
strength and stability.
8m mast supporting 120kg (EW system)
Work output = mgh = 45 pound payload x 20 feet lifting height = 900 lb - ft
If the total system mechanical efficiency were 64% (although not realistic , for a system lifting from underneath)
Work input needed = 900 / 0.64 = 1406 lb – ft
= F x d = System pull force x System pull distance
This must be done within 15 seconds,
Power = Work done per unit time = 1406 / 15 = 93.75 ft – lbf / second
550 ft – lbf / sec = 1 Hp, so for a 93% efficiency motor 93.75 / (550 *0.93) = 0.183 Hp = 137 Watts