Steering Geometry 1
i) Caster Angle:
Caster = tan -1 (dx(UB&LB)/dz(UB&LB))
=tan-1((40-0)/(525-100))
=5.37 degree
ii)Mechanical trail:
= tan(canster angle) X dz(UB&Ground)
=tan(5.37) X 100
=9.41mm
iii)King pin inclination:
KPI=tan-1(dy(UB&LB)/dz(UB&LB))
=tan-1(75/425)
=10degree
iv)Scrub:
=dy(LB&WC)- (tan(KPI) X dz(LB&Ground))
=50-tan(10) X 100
=32.35mm
v)Knigpin lateral offset:
Equation for KPI line : UB coordinates = (-657,525), LB coordinates = (-750,100)
For these coordinates slope m = dz(UB&LB)/dy(UB&LB)
=525-100/-675+750
=425/75
=5.66
so the eqn for the KPI line : (y-y1)=m(x-x1)
(y-100)=5.66(x+750)
y-5.66x-4345=0
Eqn for WC line (Parallel lines so same slope) WC coordinates : (-800,300)
(y-300)=5.66(x+800)
y-5.66x-4832=0
Perpendicula disance between two lines = KPI lateral distance
= c2-c1/square root (A.A + B.B)
=(-4832+4345/Square root (1(1) + 5.66(5.66))
=487/5.744
Spindle length =84.7mm
2) Pneumatic trail = 25mm , Mechanical trail = 9.4mm, Fy =2000N
Total restoring moment = (MT + PT) X Lateral force
=( 9.4+25) X 2000
=68.8Nm
3) Hard point suggestion for Scurb radius sign chage:
Scrub = 32.4
after sign chage scrub = -32.4 --> coordinates : (-832.4,0)
I want to change LB hard point to attain -32.4 scrub radius .
So form a line between Upper KNU BJT and scrub radius coornates:
Slope= dz(UB&Scrub)/dy(UB&Scrub)
=(525-0)/(-675+832.4)
= 3.335
Line eqn for sign changed scrub radius and UB
y-0 = 3.335(x+832.4)
y= 3.335x+2776.1
I want to have y coordinate for LB KNU BJT y = -780
by above eqn, y=3.335(-780+832.4)
y=175.
So if set UB --> (-675,525)
LB--> (-780,175) we can get same scrub radius with changed in sign ie, towards outside 32.4