Level control in a mechanical suspension for a working vehicle

A working vehicle comprising:

• a vehicle chassis;
• an undercarriage assembly connected to the vehicle chassis configured to drive the working vehicle over ground, the undercarriage assembly includes a drive roller frame mounting a front axle and a rear axle, wherein the drive roller frame is configured to rotate about the rear axle;
• a suspension system connecting the chassis to the undercarriage assembly, the suspension system comprising:
• a mechanical spring having a first end connected to one of the drive roller frame of the undercarriage assembly and the chassis, and a second end;
• and
• a hydraulic cylinder, the hydraulic cylinder having a first portion that mounts to the second end of the mechanical spring and a second portion that connects to the other of the chassis and the drive roller frame of the undercarriage assembly, such that the mechanical spring and hydraulic cylinder are arranged in series between the undercarriage assembly and the chassis, wherein the mechanical spring and hydraulic cylinder are attached to the drive roller frame intermediate the front axle and rear axle.