Power-operated scissor lift table

Abstract

A power-operated scissor table, provided with a base ( 4 ) and an upper platform or tabletop ( 5 ) connected by means of a scissor-type mechanism ( 1 - 2 ) actuated by means of a pair of thrust shafts ( 12 - 13 ) susceptible to approaching one another or moving away from one another with the collaboration of a pair of belts ( 14 ) and ( 15 ), wrapping around said shafts, which are fixed to the structure of the table at one of their ends through tension members and are fixed at their other end to respective wrap sheaves ( 17 ) and ( 18 ) assembled on a common shaft ( 19 ), the invention consists of coupling to the ends of said shaft ( 19 ) respective geared motors ( 20 - 20 ′), assisted by respective clutches ( 21 - 21 ′), such that one of said motors is operative while the other one is in a standby situation, and such that with the collaboration of an electronic circuit, when the operative motor undergoes a failure, said motor remains out of service and is declutched from the shaft ( 19 ), making the other motor automatically clutch said shaft and passing to an operative situation, keeping the functioning capacity of the table uninterrupted in spite of the failure it has undergone.

1 .- A power-operated scissor lift table, of the type of those incorporating a lower base and an upper platform or tabletop, connected to one another by means of a scissor-type mechanism on which two thrust shafts act, which thrust shafts are enveloped by a pair of belts fixed at one of their ends to the structure of the table and to conveniently power-operated wrap sheaves at their other end, characterized in that coupled at their ends to the rotation axis ( 19 ) for said wrap sheaves ( 17 ) and ( 18 ) of the belts ( 14 ) and ( 15 ) are the respective geared motors ( 20 - 20 ′), assisted by also respective clutches ( 21 - 21 ′), these elements being controlled by an electronic circuit which determines that under normal working conditions, one of the geared motors ( 20 ) is supplied and its corresponding clutch ( 21 ) is in a clutched position, whereas the other geared motor ( 20 ′) is out of service and decoupled from the shaft ( 19 ) through its clutch ( 21 ′), while due to a possible failure in the operating motor ( 20 ), said circuit cancels the power supply thereof, causes the declutching of its clutch ( 21 ) and simultaneously causes the power supply of the other geared motor ( 20 ′) and the actuation of its clutch ( 21 ′) for its coupling to the drive shaft ( 19 ) of the sheaves ( 17 ) and ( 18 ).  
   
   
       2 .- A power-operated scissor lift table according to  claim 1 , characterized in that said geared motors ( 20 - 20 ′), with their corresponding clutches ( 21 - 21 ′), are arranged outside of the structure of the table in a freely and directly accessible position for facilitating their maintenance.  
   
   
       3 .- A power-operated scissor lift table according to  claim 1  characterized in that the clutches can be replaced with manual coupling mechanisms.