Hybrid spring for a hydraulic cylinder

A method of operating a piston cylinder assembly, the piston cylinder assembly including a housing defining a housing cavity, a piston movably supported by the housing, the piston defining a piston cavity and including a support assembly within the piston cavity, the support assembly including a support rod connected at one end to the piston and having an opposite end, a flange supported on the opposite end, and a sliding member movable along the support rod, and a spring return assembly including a tension spring connected at one end to the housing, the tension spring being operable to apply a first spring force, and a compression spring connected at one end to the piston, the compression spring being operable to apply a second spring force, the compression spring being connected between the flange and the sliding member, the method comprising:

• supplying fluid to the housing cavity to apply a fluid force to the piston to extend the piston out of the housing;
• moving the sliding member toward the flange and applying the second spring force;
• applying a spring return force to the piston, the spring return force including the first spring force and the second spring force in series;
• and
• when the spring return force of the spring return assembly is greater than the fluid force, retracting the piston into the housing.

A piston cylinder assembly comprising:

• a housing defining a housing cavity;
• a piston movably supported by the housing, fluid supplied to the cavity applying a fluid force to cause the piston to extend out of the housing;
• and
• a spring return assembly connected between the housing and the piston and operable to apply a spring force to cause the piston to retract into the housing, the spring return assembly including
• a first spring member connected at one end to the housing and having an opposite end, the first spring member being operable to apply a first spring force, and
• a second spring member connected at one end to the piston and having an opposite end, the second spring member including a pair of compression springs arranged in parallel and operable to apply a second spring force, the opposite end of each of the first spring member and the second spring member cooperating to apply the first spring force and the second spring force in series.

A spring return assembly for a piston cylinder assembly, the piston cylinder assembly including a housing defining a housing cavity, and a piston defining a piston cavity and movably supported by the housing, fluid supplied to the housing cavity applying a fluid force to cause the piston to extend out of the housing, the spring return assembly comprising:

• a support assembly positioned within the piston cavity, the support assembly including a support rod connected at one end to the piston and having an opposite end, a flange supported on the opposite end, and a sliding member movable along the support rod;
• a tension spring connectable at one end to the housing and having an opposite end, the tension spring being operable to apply a first spring force;
• and
• a compression spring connectable at one end to the piston and having an opposite end, the compression spring being operable to apply a second spring force, the opposite end of each of the tension spring and the compression spring cooperating to apply the first spring force and the second spring force in series to cause the piston to retract into the housing.

A method of operating a piston cylinder assembly, the piston cylinder assembly including a housing defining a housing cavity, a piston movably supported by the housing, and a spring return assembly including a tension spring connected at one end to the housing, the tension spring being operable to apply a first spring force, a first compression spring, and a second compression spring arranged in parallel with the first compression spring, each of the first compression spring and the second compression spring being connected at one end to the piston, the first compression spring and the second compression spring being operable to apply a second spring force, the method comprising:

• supplying fluid to the housing cavity to apply a fluid force to the piston to extend the piston out of the housing;
• applying a spring return force to the piston, the spring return force including the first spring force and the second spring force in series;
• and
• when the spring return force of the spring return assembly is greater than the fluid force, retracting the piston into the housing.