Hollow elastomeric spring

A spring comprising:

• first and second rigid end members arranged spaced apart and one opposed relative to the other,
• a body of elastomeric material which extends between and is bonded to said opposed rigid end members whereby compression forces acting in a first direction on said rigid end members are resisted by compression of the elastomeric body, the maximum external dimension of the bonded area between the first rigid member and body being less than that of the bonded area between the second rigid member and body,
• the body of elastomeric material being of a substantially symmetrical shape as considered in any cross-section about a major axis of the spring extending in said first direction, the body of elastomeric material being substantially solid in the vicinity of the first of said rigid end members and of a substantially hollow tubular shape in the vicinity of the second of said rigid end members over between 10 and 80% of the length of the body between said opposed rigid end members,
• said body of elastomeric material in the absence of applied force in the first direction being of progressively increasing external cross-sectional dimension over a first part of the length of the body extending from the first rigid end member and of progressively decreasing external cross-sectional dimension over a second part of the length of the body extending to said second rigid end member,
• said second part extending over at least 10% of the length of the body and said first and second parts each being of a curved convex external profile as considered in a plane containing said major axis, the curved external profile of the first part of the length of the spring having at least one centre of curvature and said at least one centre of curvature lying further from the first rigid member in a direction towards the second rigid member than that transverse plane at which the external dimension of the body is a maximum, and
• any centre of curvature of the curved external profile of the second part of the length of the spring lying nearer to the first rigid member than any centre of curvature of the curved external profile of the first part of the length of the spring.

A spring comprising:

• first and second rigid end members arranged spaced apart and one opposed relative to the other,
• a body of elastomeric material which extends between and is bonded to said opposed rigid end members whereby compression forces acting in a first direction on said rigid end members are resisted by compression of the elastomeric body, the maximum external dimension of the bonded area between the first rigid member and body being less than that of the bonded area between the second rigid member and body, the body of elastomeric material being of a substantially symmetrical shape as considered in any cross-section about a major axis of the spring extending in said first direction, the body of elastomeric material being substantially solid in the vicinity of the first of said rigid end members and of a substantially hollow tubular shape in the vicinity of the second of said rigid end members over between 50 and 70% of the length of the body between said opposed rigid end members,
• said body of elastomeric material in the absence of applied force in the first direction being of progressively increasing external cross-sectional dimension over a first part of the length of the body extending from the first rigid end member and of progressively decreasing external cross-sectional dimension over a second part of the length of the body extending to said second rigid end member,
• said first part extending over between 60 and 90% of the length of the body and said first and second parts each being of a curved convex external profile as considered in a plane containing said major axis, the curved external profile of the first part of the length of the spring having at least one centre of curvature and said at least one centre of curvature lying further from the first rigid member in a direction towards the second rigid member than that transverse plane at which the external dimension of the body is a maximum, and
• any centre of curvature of the curved external profile of the second part of the length of the spring lying nearer to the first rigid member than any centre of curvature of the curved external profile of the first part of the length of the spring.