Land vehicles – Suspension modification enacted during travel
Reexamination Certificate
2011-03-01
2011-03-01
Dickson, Paul N (Department: 3616)
Land vehicles
Suspension modification enacted during travel
C280S755000, C180S282000, C414S631000, C187S222000
Reexamination Certificate
active
07896358
ABSTRACT:
A lift truck includes a magneto-rheological damper coupled between the base frame and a frame holding a vertically sprung suspended wheel. The damper is electrically connected to a vehicle control system, which increases and decreases the damping force as a function of at least one of a weight of a load on the forks of the lift truck, a height of the mast of the lift truck, and a speed of the lift truck. As the weight of the load, height of the mast and speed of the vehicle increase, the damping force is increased. As the weight of the load, height of the mast, and speed of the vehicle decrease, the damping force is decreased. When the damper is activated to increase the damping force, the truck can maintain a four point stance, providing a larger footprint for the center of gravity, thereby limiting truck sway or oscillation. When the damper is not active, or the damping force is increased, as, for example, during unloaded operation, the suspension of the truck is relatively soft, providing a smoother ride, thereby increasing operator comfort and productivity.
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De Man P. et al., “An Investigation of a Semiactive Suspension for a Fork Lift Truck,” Vehicle System Dynamics, vol. 43, No. 2, Feb. 2005, p. 107-119.
European Search Report 08017651.1 mailed on Apr. 7, 2009.
Dickson Paul N
Frisby Keith
Krumenacher Thomas J.
Quarles & Brady LLP
The Raymond Corporation
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