Patent GB-116737-A (GB)
Title: Improvements in or relating to the Springing of Motor Road Vehicles.
Inventor: WICKMAN AXEL CHARLES
IPC: B60G17/02
Filed: 1917-05-18
Abstract: 116,737. Wickman, A. C. May 18, 1917. Semi-elliptic and laminar springs. - The point about which the leaf spring of a motor vehicle flexes is automatically varied according to the load by mechanism operated by vertical vibrations of the axle, means operable by hand also being provided for varying the action of the automatic device to cause an adjustment of the stiffness of the spring irrespective of the load. Figs. 1 and 2 show a cantilever spring with a movable centre pivot. The centre of the spring has an areshaped block bearing against a roller d carried by arms pivoted about a transverse shaft e on the chassis. The block has a rack c<5> engaged by a pinion d<3>, Fig. 3, on the roller d which has a sprocket-wheel d<4> geared to a sprocket-wheel f loose on the shaft e. A sprocketwheel f<1> integral with a wheel f is geared to a sprocket wheel f<2> on a shaft f<3> which has a bevel wheel f<4> gearing with a bevel wheel on a longitudinal shaft g, Fig. 2. The shaft g carries two oppositely toothed ratchet wheels adapted to be engaged by pawls on vibrating levers i<1>, i<2> loose on the shaft g. The pawls are normally held out of engagement by springs and are connected by rods i', Fig. 4, to bell crank levers i<6> pivoted on the ends of the levers i<1>, i<2> and provided with pins i<4> adapted to be engaged by a looped frame k carried by the axle casing b<1>. Vertical oscillations of the axle normally cause the pawls on the levers i<1>, i<2> to engage the ratchet wheels alternately and turn the shaft g equal amounts in opposite directions, return movements of the levers being limited by stops j. Should the mean position of the axle change owing to a variation of load, unequal movements of the levers are effected and a step-by-step rotation of the shaft g takes place until the fulcrum d of the spring is adjusted to suit the load. The stops are carried by arms j<1> on a sleeve j<2> surrounding the shaft g and provided with a lever j<3> adapted to be moved by Bowden mechanism so as to alter the position of the stops. An indicator on the dashboard shows the position of the stops. Modifications are described in which the are-shaped surface is carried respectively by one end of a cantilever spring and by one end of a semi-elliptic spring, movement of the fulcrum being effected by a lever and link connected to a nut on a screw-threaded shaft in the position of the shaft g. An alternative means for turning the shaft g is shown in Fig. 18 in which a lever t<2> vibrated by the rear axle is attached to a casing t loose on the shaft g. In the casing t a spindle s<3> having two parallel arms, one of which, (not shown), carries a friction block adapted to jamb against a pulley on the shaft g when relative movement takes place between the arm and the casing t. The other arm s<4> carries a block s<5> adapted to slide on a curved rod s<6> between springs s<9> of equal strength which abut on a block s' carried on a boss connected to a lever s<8> which may be manually adjusted through Bowden mechanism. The differential pressure of the spring s<9> on the block s<5> causes the spindle s<3> to be turned relative to the casing and jamb the friction block on to the pulley on the shaft g which is then turned in one direction or another by the vibration of the arm t<2>. To prevent overstrain of the parts when the mechanism has reached the limit of adjustment, couplings may be introduced between the spindle f<3> and wheel f<4>, Fig. 3, or between the shaft g and a screwed-threaded part concentric with it, which are adapted to slip when a limiting torque is exceeded. The couplings described comprise corrugated engaging-surfaces held together by springs adapted to yield axially of the shafts concerned.