Steering Mechanisms

Steering principle C

A B

b

a

φ θ E

I

F

EI EF  FI a  FI cot     AE AE b FI FI cot    CF b a  FI FI a  cot   cot     b b b

Davis steering

G

E

F

α

H

α h

B

D A

C

AC - GH = 2c c tanα = h c+x tanα + φ = h c-x tanα - θ = h

φ θ

F

E

G

H

h

B

φ

A x

c h  tan  c  x cx tan   tan   tan         h 1  tan  tan  1  c h tan  h xh  c  h tan   c  x  c 2 h tan   cx h tan   tanφ = 2 h + cx + c 2 c h  tan  tan   tan  cx tan         1  tan  tan  1  c h tan  h xh  c  h tan   c  x  c 2 h tan   cx h tan   tanθ = 2 h - cx + c 2 tan      

α

φ

α

Davis steering

D C

θ

x I

h 2  cx  c 2 h 2  cx  c 2 h 2  cx  c 2 h 2  cx  c 2 2cx 2c , cot    cot   cot     cot   cot    xh xh xh xh xh h  cotf - cotq = 2tana cot  

For correct steering cotφ - cotθ =

a a a  2 tan    tanα = b b 2b

Since tan α is a constant of design, this mechanism provides perfect steering