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Joints and Linkages in Mechanics

This document discusses joints and linkages. It defines common joints like prismatic joints, spherical joints, and hinge joints. It then analyzes four-bar linkages and describes different configurations like crank-rocker, double-crank, and rocker-crank linkages. The document also discusses degrees of freedom of linkages and provides examples of linkages used in machines like front loaders and SCARA robots.

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Alessio Scarabelli
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49 views10 pages

Joints and Linkages in Mechanics

This document discusses joints and linkages. It defines common joints like prismatic joints, spherical joints, and hinge joints. It then analyzes four-bar linkages and describes different configurations like crank-rocker, double-crank, and rocker-crank linkages. The document also discusses degrees of freedom of linkages and provides examples of linkages used in machines like front loaders and SCARA robots.

Uploaded by

Alessio Scarabelli
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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JOINTS and LINKAGES

A. Vania
Politecnico di Milano, Dept. of Mechanical Engineering, Milan, Italy
JOINTS 2

prismatic joint

spherical 3D

helical joint
spherical 2D

plane on plane

hinge (or pin joint)

APPLIED MECHANICS – Prof. Andrea VANIA


JOINTS 3

translations
degree of
freedom

rotations
free
free
name

sphere between
parallel planes

sphere in a
cylinder

cylinder between
parallel planes

hinge (or pin joint)


spherical

sphere in a
cylinder with
groove

planar

spherical with
groove

toric

cylindrical

cylindrical with
groove

rotoidal

prismatic

pin joint in a bridge pillar joint rigid joint


APPLIED MECHANICS – Prof. Andrea VANIA
FOUR-BAR LINKAGE 4

s l

Four-bar linkage: shortest link s,


longest link l, intermediate length links p and q
p

driver

driver
s

s+l < p+q


(a) Crank - rocker s+l < p+q
(b) Double - crank

APPLIED MECHANICS – Prof. Andrea VANIA


FOUR-BAR LINKAGE 5

driver
driver

s
(full rotation of
s the coupler link
is possible)
s+l < p+q s+l < p+q
(c) Rocker - crank (d) Grashof Rocker-rocker

s+l = p+q

s+l < p+q


(f) Change-Point Mechanism
in Toggle Configuration
(e) Non-Grashof Rocker-rocker
(triple rocker)

APPLIED MECHANICS – Prof. Andrea VANIA


LINKAGES 6

APPLIED MECHANICS – Prof. Andrea VANIA


CRANK AND SLOTTED LINK 7

Configuration “a” Configuration “b”

APPLIED MECHANICS – Prof. Andrea VANIA


LINKAGE DOFs 8

N = 3 ( m − 1 ) − 2 C1 − C2

Front loader

shovel

APPLIED MECHANICS – Prof. Andrea VANIA


“SCARA” ROBOTS 9

Selective Compliance Assembly Robot Arm

end effector
end effector
(tongs)
(e.g. screwdriver)

N = 6 ( m − 1 ) − 5 C1 − 4 C2 − 3 C3 − 2 C4 − C5
SCARA robots
APPLIED MECHANICS – Prof. Andrea VANIA
10

APPLIED MECHANICS – Prof. Andrea VANIA

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