Safety braking device for a unit moving along a surface, in particular for a lift car

A safety braking device for stopping a unit movable along a surface, in particular a lift car, when the speed of the unit becomes superior to a predetermined speed, comprising a case for fixing to the moving unit, a shaft rotatively mounted in the case and having one end outside the case, a drive wheel carried by said one end for slip-free engagement with said surface to be rotated by said surface upon said movement of said unit and thereby rotate the shaft, a disc assembly comprising fixed annular discs having an inner periphery and connected to be held against rotation relative to the case and movable discs connected to rotate with the shaft, the fixed discs being interposed between the movable discs and the fixed discs and movable discs being coaxial to and movable axially of the shaft, a support member connected to rotate with the shaft by releasable connecting means, a centrifugal element carried by the support member, an abutment which is fixed relative to the case, a gear wheel connected to rotate with the support member and coaxial with the shaft, axial thrust means for urging the discs together and comprising a thrust assembly comprising a screw which has a head located at one end of the disc assembly and extends freely through aligned openings of the movable discs and is disposed radially inwardly of said inner periphery and outwardly of the shaft and a gear pinion screwthreadedly engaged on the screw beyond an opposite end of the discs and meshed with the gear wheel, the centrifugal element being movable between a position of rest in which position it is incapable of encountering the abutment and an outer position in which outer position it is brought by the effect of centrifugal force and is capable of encountering the abutment and stopping rotation of the support member beyond a reference speed of rotation of the support member corresponding to said predetermined speed, said releasable connecting means being released and thereby allowing the stoppage of the support member while allowing rotation of the shaft when the centrifugal element encounters the abutment, whereby continued rotation of the shaft causes the pinion to roll around the gear wheel and move along said screw towards the screw head, the device further comprising a second thrust assembly comprising said headed screw and gear pinion similar to the first-mentioned thrust assembly but having an opposite hand of the screwthread of the screw, a second centrifugal element being carried by the support member and capable of engaging in the opposite direction of rotation of the shaft, a second abutment which is fixed relative to the case.

A safety braking device for a unit movable along a surface, in particular for a lift car, comprising a case for fixing to the moving unit, a shaft rotatively mounted in the case and carrying at one end, outside the case, a drive wheel for slip-free engagement with said surface to be rotated by said surface upon said movement of said unit, fixed discs connected to be held against rotation relative to the case, movable discs connected to rotate with the shaft, the fixed discs being interposed between the movable discs and the fixed discs and movable discs being movable axially of the shaft, a support member, a centrifugal element carried by the support member, an abutment which is fixed relative to the case, means connecting the support member to the shaft to be rotated by the shaft, means for axially urging the discs together for braking the shaft relative to the case, said urging means comprising first screwthreaded means, second screwthreaded means screwthreadedly engaged with the first screwthreaded means and combined with the movable discs to urge the discs together upon rotation of the first screwthreaded means, gear train means drivingly connecting the support member to the first screwthreaded means for rotating the first screwthreaded means upon rotation of the support member, the centrifugal element being movable between a position of rest in which position it is incapable of encountering the abutment and an outer position in which outer position it is brought by the effect of centrifugal force and is capable of encountering the abutment and stopping rotation of the support member beyond a reference speed of rotation of the support member, said means connecting the support member to the shaft being capable of allowing the stoppage of the support member while allowing rotation of the shaft when the centrifugal element encounters the abutment, the device further comprising a safety screw screwthreadedly engaged in an end of the shaft and extending through said support member, means for preventing the safety screw from rotating relative to the support member, a device for driving said unit, and a switch for controlling the operation of the unit-driving device, said safety screw being capable of moving axially of the shaft and engaging said switch for cutting off the supply of current to said unit-driving device a predetermined period after stoppage of the support member by the encounter of the centrifugal element with the abutment.

A safety braking device for stopping a unit movable along a surface, in particular a lift car, when the speed of the unit becomes superior to a predetermined speed, comprising a case for fixing to the moving unit, a shaft rotatively mounted in the case and having one end outside the case, a drive wheel carried by said one end for slip-free engagement with said surface to be rotated by said surface upon said movement of said unit and thereby rotate the shaft, a disc assembly comprising fixed annular discs having an inner periphery and connected to be held against rotation relative to the case and movable discs connected to rotate with the shaft, the fixed discs being interposed between the movable discs and the fixed discs and movable discs being coaxial to and movable axially of the shaft, a support member coaxially mounted on and frictionally connected to the shaft, a centrifugal element carried by the support member an abutment which is fixed relative to the case, a gear wheel connected to rotate with the support member and coaxial with the shaft, axial thrust means for urging the discs together and comprising a thrust assembly comprising a screw which has a head located at one end of the disc assembly and extends freely through aligned openings of the movable discs and is disposed radially inwardly of said inner periphery and outwardly of the shaft and a gear pinion screwthreadedly engaged on the screw beyond an opposite end of the discs and meshed with the gear wheel, the centrifugal element being movable between a position of rest in which position it is incapable of encountering the abutment and an outer position in which outer position it is brought by the effect of centrifugal force and is capable of encountering the abutment and stopping rotation of the support member beyond a reference speed of rotation of the support member corresponding to said predetermined speed, said frictional connection allowing the stoppage of the support member while allowing rotation of the shaft when the centrifugal element encounters the abutment whereby continued rotation of the shaft causes the pinion to roll around the gear wheel and move along said screw towards the screw head.