Tapered spring leaf suspension for driver tandem axle assembly

Claim 2

In a motor vehicle suspension, the improvements comprising: a driven axle; a frame for the vehicle; an upper tapered spring leaf having a thickness along a substantial length thereof at least 30 percent greater than the thickness align another substantial length thereof; a lower tapered spring leaf having a thickness along a substantial length thereof at least 30 percent greater than the thickness along another substantial length thereof; means securing said spring leaves to the axle near the centers of said spring leaves; a bracket attached to said frame forwardly of said axle; a flange on saiD bracket; a camming surface on the underside of said flange; said upper spring leaf and said lower spring leaf being shaped and secured with respect to each other comprising means separating the forward portion of said upper spring leaf at a distance from said camming surface when said vehicle is relatively unladen; means securing the forward end of said lower spring leaf on said bracket; a second camming surface attached to said frame and in contact with the rear portion of said upper spring leaf; said upper spring leaf and said lower spring leaf being shaped and secured with respect to each other comprising means separating the rear portion of said lower spring leaf at a distance from said upper spring leaf when the vehicle is in a relatively unladen condition; and said upper spring leaf and said lower spring leaf being shaped and secured with respect to each other, and said second camming surface transmitting to the rear portion of said upper spring leaf a portion of the structural load on the suspension when the vehicle is more fully laden comprising means reducing said last-mentioned distance and causing the forward upper portion of the upper spring leaf and said rear portion of the lower spring leaf bear a portion of the structural load on the suspension when the vehicle is more fully laden; the forward portion of the upper spring leaf and the portion of the lower spring leaf and the portion of the lower spring leaf between said bracket and axle being of a taper with increasing thickness rearwardly from said bracket to said axle.

Claim 3

The apparatus in claim 1 wherein the distance separating the rear portion of said lower leaf from the rear portion of said upper leaf is the same as the distance separating the forward end o the upper leaf from the forward camming surface when the vehicle is relatively unladen.

Claim 4

The apparatus in claim 1 wherein the forward end of said upper leaf is bent over into a hooklike shape extending forwardly of said means securing the forward end of the lower leaf on said bracket.

Claim 5

The apparatus in claim 1 and means for adjusting the forward or rearward translation of said axle for precise positioning thereof with respect to means of driving the wheels placed on said axle.

Claim 6

The device of claim 1 wherein a second axle is disposed rearwardly of said driven axle is disposed rearwardly of said driven axle and a like second suspension is provided for said second axle; a walking beam journaled adjacent the center thereof to said frame; said second camming surfaces comprising the end portions of said walking beam and including rubber members vertically spaced below and secured to said end portions of said walking beam; the rear portions of each of said upper and lower spring leaves positioned in said space defined between the end portions of said walking beam and the associated rubber members whereby said rubber members provide a limit against downward motion of each said spring leaf rear portions.

Claim 7

The apparatus of claim 1 wherein said means securing the forward end of the lower spring leaf has a rubber bushing upon which said forward end is journaled.

Claim 8

The device of claim 1 wherein a second axle is disposed rearwardly of said driven axle and a like second suspension is provided for said second axle; a walking beam journaled adjacent the center thereof to said frame; said camming surfaces comprising the end portions of said walking beam, and said walking beam being relatively rigid compared to said spring leaves.

Claim 9

The device of claim 1 wherein said means securing the forward end of said lower spring leaf includes means journaling said last-mentioned spring leaf to said bracket.

Claim 10

The device of claim 1 wherein a second axle is disposed rearwardly of said driven axle and a like second suspension is provided for said second axle; a walking beam journaled adjacent the center thereof to said frame; said second camming surfaces comprising the end portions of said walking beam, and saiD walking beam having a spring rate of the same order of magnitude with respect to said spring leaves.

Claim 11

The apparatus of claim 1 wherein the forward end of said lower spring leaf comprises a first arm and the rear portion of said lower spring leaf comprises a second arm, the spring rate in the first-mentioned arm being different from the spring rate in the second mentioned arm.

Claim 12

The apparatus of claim 1 including a longitudinally extending walking beam journaled at the center thereof to said frame rearwardly of said driven axle, said second camming surface being fixed to the forward end of said walking beam; said driven axle being a forward driven axle; a rear driven axle constituting, together with said forward axle, a second upper tapered spring leaf having a thickness along a substantial length thereof at least 30 percent greater than the thickness along another substantial length thereof; a second lower tapered spring leaf having a thickness along a substantial length thereof at least 30 percent greater than the thickness along another substantial length thereof; means securing said second upper spring leaf and said second lower spring leaf to said rear axle near the centers of said second upper and lower spring leaves; an aft bracket attached to the frame forwardly of said rear axle; a flange on said aft bracket; a camming surface on the underside of said flange on said aft bracket; said second upper spring leaf and said second lower spring leaf being shaped and secured with respect to each other comprising means separating the forward portion of said second upper spring leaf at a distance from said camming surface on said aft bracket when said vehicle is relatively unladen; means securing the forward end of said second lower spring leaf on said aft bracket; a camming surface on the aft end of said walking beam and in contact with the rear portion of said second upper spring leaf; said second upper spring leaf and said second lower spring leaf being shaped and secured with respect to each other comprising means separating the rear portion of said second lower spring leaf at a distance from said second upper spring leaf when the vehicle is in a relatively unladen condition; and said second upper spring leaf and said second lower spring leaf being shaped and secured with respect to each other, and said camming surface on the aft end of said walking beam transmitting to the rear portion of said second upper spring leaf a portion of the structural load on the suspension when the vehicle is more fully laden comprising means reducing said last-mentioned distance and causing the forward upper portion of the second upper spring leaf and said rear portion of the second upper spring leaf and said rear portion of the second lower spring leaf to bear a portion of the structural load on the suspension when the vehicle is more fully laden; the forward portion of the second upper spring leaf and the portion of the second lower spring leaf between said aft bracket and said rear axle being of a taper with increasing thickness rearwardly from said aft bracket to said rear axle.

Claim 13

The apparatus of claim 1 and means continuously and smoothly increasing the share of structural load on said rear portion of said lower spring leaf placed by the vehicle on the suspension as the vehicle is more fully laden.

Claim 14

The apparatus of claim 1 and said forward portion of said upper spring leaf being shaped and positioned with respect to said camming surface and said flange of said forward bracket comprising means preventing said forward portion of said upper spring leaf from bearing a structural load until a predetermined threshold of load is placed on the vehicle above an unladen condition.