Bushing type mount with triple spring rate

Claim 1

In an isolation mount for absorbing shock loading including a stub shaft, mounting means providing at least a double spring rate including a first spring rate from substantially zero deflection to a first deflection limit and a second spring rate from said first deflection limit to a second deflection limit, said second spring rate being higher than said first spring rate, said second deflection limit being greater than said first deflection limit, wherein said mounting means comprises annular inner and outer bushings, said inner bushing having a diameter less than the diameter of said outer bushing and defining an annular space therebetween, said outer bushing having a radially inner face and said inner bushing having a radially outer face which define the radial limits of said space, an annular mounting ring intermediate said faces, said mounting ring defining a radially outer portion being generally axially directed, and a pair of generally axially directed radially inner portions on opposite sides of said radially outer portion, said outer and inner portions being connected by a pair of generally radially directed side walls, and further including a pair of annular, resilient outer bushing members intermediate said inner portions and said radially inner face, and an inner resilient bushing member intermediate said outer portion and said radially outer face, and wherein said outer portion is spaced from said inner face by an outer gap.