Patent ID: 7137876
Filing Date: 2006-11-21
Classification: B24B

Abstract:
1. In a floor burnisher having a wheeled frame and a head assembly including a motor driving a polishing element, a lift mechanism for moving said head assembly between a raised position for transport or storage and a lowered use position of readiness, said lift mechanism mounted comprising: a main lift assembly mounted to said frame for pivotal motion about a horizontal axis, said main lift assembly pivotally mounted to said head assembly to carry the same; a first counterbalancing mechanism connected between said frame and said main lift assembly to provide a first counterbalancing force on said main lift assembly to offset at least partially the weight of said head assembly; a second counterbalancing mechanism including an adjusting mechanism connected between said frame and said main lift assembly to provide a second counterbalancing force on said main lift assembly adding to said first counterbalancing force, said adjusting mechanism adjusting said second counterbalancing force and thereby adjusting the downward force on said head assembly during use when said polishing element is driven in rotation by said motor and creates suction which forces said polishing element into engagement with a floor surface to be burnished, said second counterbalancing mechanism including a link pivotally connected at one end to said frame; an actuator under control of an operator to pivot said link about its pivot connection to said frame; and a spring-biased device including a spring and having a first end connected to said lift mechanism, a second end connected to said frame, said spring being arranged to exert an upward counterbalancing force on said lift mechanism tending to raise said head assembly, said link controlling the compression of said spring such that the angular position of said link about its pivot connection adjusts the amount of force exerted by said second counter-balancing mechanism.