Model 13: Escort / quick return motion for the x-component of a coupler curve

used in a sod-perforating machine

 

Kinematic scheme:

 

Dimensions:

 

 

Dimensions [m]

a

0.0360

b

0.08

c

0.1565

d

0.2043

e

0.1635

f

0.0801

g

0.172

h

0.1

u

0.0903

v

0.0665

w

0.2

r

p/20

pitch of belt

0.005

belt length

0.5

 

 

Explanation:

The mechanism frame is placed at a tractor that is driving across the field. The belt represents the field in the model. While driving, the mechanism punches vertical holes in the field. This is required for draining off rain water. The path of point P (and of point P/ due to the parallelograms) is a coupler curve of the four-bar linkage A0ABB0, such that its horizontal component moves approximately with opposite tractor speed when the punch perforates the soil. The horizontal motion components have been depicted in the figure below.

Literature: Klein Breteler, A.J.: Optimization study of a sod-perforating machine. Proceedings of the 8th IFToMM World congress, pp. 363-366, Prague, 1991.

 

Remarks: The real mechanism makes 0.4 m deep holes with a pitch of 0.1 m. The machine contains eight of these mechanisms, arranged in parrallel planes and driven from the same crank shaft. Each mechanism carries two punches, such that a row of 16 punches will operate parallel at distances of 0.1 m for a working trail width of 1.6 m. The model has been scaled 1:5 compared to the real mechanism. On the backside of the frame plate a pair of gears connects the crank and the belt wheel (reduction ratio 1:5).

 

 

 

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