Davis Steering Steering Gear Mechanism 1533e

The Davis steering is an exact steering gear mechanism.the slotted links AM and BH are attached to the front wheel axle, which turns on pivots A and B respectively . the road CD is constrain to move in the direction of its length, by the sliding member at P and Q. these constrain are connected to the slotted links AM and BH by a sliding and a turning member at each end. the steering is effected by moving CD to right or to left of normal position. C`D` show the position of CD for turning to left. let a=vertical distance between AB and CD. b=Wheel base. c= Distance between the pivots A and B of the front axle. d=Horizontal distance between AC and BD. x=distance move by AC to AC`=CC`=DD`, and α=Angle of inclination of the link AC and BD , to vertical. From triangle AA`C` tan(α+φ)=A`C`/AA`=d+x/a From triangle AA`c tanα=A`C /AA`=d/a From triangle BB`D` tan(α-Θ)=B`D`=d-x/a

we know that tan(α+φ)=tanα+tanφ/1-tanα*tanφ =d+a*tanφ/a-d*tanφ (d+x)(a-d*tanφ)=a(d+a*tanφ) tanφ=a*x/(a^2+d^2+d*x) similarly , from tan(α-Θ)=d-x/a We get tanΘ=a*x/(a^2+d^2-d*x) we know that for correct steering , cotφ-cotΘ=c/d 1/tanφ-1/tanΘ=c/d (a^2+d^2+d*x)/a*x-(a^2+d^2-d*x)/a*x=c/b 2d*x/a*x=c/d 2tanα=c/d (d/a=tanα) Note: through the gear is theoretically correct, but due the presence of more sliding , the wear will be increased which produce slackness between the sliding surface, thus eliminating the original accuracy. Hence Davis steering gear is not in common use.

Davis steering gear mechanism Posted by on October 14th, 2011 Davis steering gear mechanism is the one which gives us exact steering alignment. In this mechanism we have two slotted links AM and BH, these two links are attached with front wheel axle and can move on fixed points A and B. On the other hand rod CD is restricted to move along the direction of front wheel axis by sliding at P and Q. this rod CD is attached with slotted links AM and BH with the help of sliding and turning pair.

Davis steering gear mechanism

To know its relation, consider a = Vertical distance between AB and CD b =Wheel base d =Horizontal distance between AC and BD c =Distance between pivots A and B of front axle x =Distance moved by AC to AC’ =CC’ = DD’ α =Angle of inclination of links AC and BD Let us consider driver takes a left turn, then from triangle AA’C’ tan (α + φ) = A’C’ / A’A’ = ( d + x ) / a Now triangle AA’C tan α = A’C /AA’ = d / a From triangle AA’C tan ( α – θ ) = B’D’ / BB’ = ( d – x ) / a According to following formula tan ( α + φ ) = [tan α + tan φ] / [ 1 – tan α.tan φ] ( d + x ) / a = [d/a + tan φ] / [ 1 – (d/a).tan φ] (d + x)(a – d tanφ) = a.(d + a tan φ) tan φ = ax / [a2 + d2 + dx] Similarly we will find out tan θ = ax / [a2 + d2 – dx]

Since we know that cot φ – cot θ = c / b [(a2 + d2 + dx) / a.x] – [(a2 + d2 – dx) / a.x] = c / b After solving we will get desire result 2d / a = c / b Since d / a = tan α Therefore tan α = c / 2b This method is not used now-a-days because of more sliding but it provides us accurate alignment. So if we remove sliding from the mechanism by maintaining same alignment then we will a perfect steering gear mechanism.