Patent ID: 11882788
Assignee: AGCO INTERNATIONAL GMBH
Field: Other special machines (Mechanical engineering)
Classification: CPC A  F | IPC A  F

Claim 3:
4. An agricultural machine comprising:
a knife bar supported by a frame;
a drive apparatus operable to drive the knife bar in a reciprocating linear motion at a variable drive frequency;
at least one gas spring coupled to the knife bar for applying a restoring force to the knife bar toward a neutral position when in motion, wherein the at least one gas spring has a variable modulus of elasticity that is dependent upon the drive frequency; and
a hydraulic cylinder having a pair of fluid chambers separated by a piston connected to the knife bar, wherein the reciprocating linear motion of the knife bar is translated into reciprocating motion of the piston, wherein the at least one gas spring comprises a pair of air-charged accumulators each connected to a respective one of the fluid chambers and having a respective flow control valve connected thereto, wherein the valves are configured to control a flow of air in to, and out of, the respective accumulators to control a modulus of elasticity of the accumulators.