# Grashof's Four bar Law mechanism

It said that in four bar mechanism if sum of the shortest bar  (s)+ longest bar (l)  less than or equal to length of other two bar then we will get either crank crank mechanism or crank rocker mechanism

shortest length =  50 mm                        50+150 = 200

longest length  = 150 mm

length of p = 120mm

length of q  = 130 mm  120+ 130 = 250

s+l <=  (p+q)

1 . Crank Rocker mechanism condition : if  adjacent to the shortest bar is fixed then we will get crank rocker mechanism

2. Crank Crank mechanism : if the shortest length is fixed then we will get crank crank mechanism

3. Rocker Rocker mechanism : if the opposite side to the shortest crank is fixed then we will get crank crank mechanism

if the s+l =p+q ,what is the type of linkage

Special case s + l = p+q (then  crank crank)

Grashof's four bar mechanism is very important i know it looks like what the big deal but when you trying to make mechanism you will realise how much important it is

grashof law Application

• Crank mechanism
• Pump mechanism