Movable access ramp for vehicles

Claim 2

A movable device forming a foldable access ramp to interconnect a vehicle with an outside platform, said ramp being adapted to swing in parallel relation to a vertical plane so as to be raised into inoperative stowed position on said vehicle and lowered into operative working position to rest at least partially on said platform, said ramp comprising at least two successive ramp sections pivotally interconnected endwise in the longitudinal direction and the first one of which forming an innermost section is pivotally connected to said vehicle and attached with at least one point of said ramp section to at least one constantly tensioned handling cable winding up on at least one winch located on said vehicle whereas the other or second ramp section may be folded back and downwards against and along said innermost ramp section and is attached to at least one handling cable controlling its outward extension for raising said other ramp section into the extended position in at least approximatively aligned registering relationship with said innermost ramp section in the lowered working position, wherein the improvement consists in that each handling cable for controlling the outward extension of said second ramp section is connected to means for automatically tensioning and taking up the slack of said cable through the action of potential energy, said means being provided on said vehicle and comprising self-acting means for stopping said cable and holding it unidirectionally against motion, said latter means being adapted to form a stationary fastening means for generating, through blocking of the effective useful length of said cable, a tractive reaction force tending to raise said second ramp section into its outward extended position during the lowering motion through gravity of said innermost ramp section which is constantly suspended from each one of its own handling cables.

Claim 3

A device according to claim 1, comprising selectively adjustable load transfer means for varying at will the bearing reaction force of said ramp onto said platform in the working extended position of the ramp to thereby transfer at least one selectively variable part of the weight and instant load of said second ramp section to either of said innermost ramp sections and of independent auxiliary supporting means provided on said vehicle.

Claim 4

A device according to claim 1, wherein said self-acting means for automatically stopping said handling cables and unidirectionally Holding same against motion are arranged so as to be operative only from a given angle of slope of said innermost ramp section with respect to the vertical direction during the starting period of lowering motion thereof.

Claim 5

A device according to claim 1, wherein each handling cable for controlling the relative outward extension of said second ramp section is reeved over at least one elevated loose guide pulley mounted on said vehicle and terminates in a movable counterweight forming said automatic tensioning and slack taking-up means whereas said automatic means for stopping said handling cables and unidirectionally holding same against motion consist of a stationary stop means limiting the upward motion of said counterweight provided on said vehicle.

Claim 6

A device according to claim 2, wherein each handling cable controlling the relative outward extension of said second ramp section is reeved on at least one elevated loose guide pulley mounted on said vehicle and terminates into a movable counterweight forming said tensioning and slack taking-up means whereas said automatic means for stopping said handling cables and unidirectionally holding same against motion consist of a stationary stop means limiting the upward motion of said counterweight and provided on said vehicle, the weight of each counterweight being selectively adjustable so that said counterweight forms said load transfer means.

Claim 7

A device according to claim 2, wherein each handling cable controlling the relative outward extension of said second ramp section is connected to a stationary fastening point provided on said vehicle through the medium of an adjusting member having a selectively variable length and forming one aforesaid tensioning and load transfer means.

Claim 8

A device according to claim 2, wherein each handling cable controlling the relative outward extension of said second ramp section is connected to a linear-displacement type pressure fluid operated actuator generating a selectively adjustable force and forming one aforesaid tensioning and load transfer means.

Claim 9

A device according to claim 1, wherein each handling cable controlling the relative outward extension of said second ramp section is connected to a stationary fastening point provided on said vehicle through the medium of at least one resiliently deformable spring-like member constituting said automatic tensioning and slack taking-up means whereas said automatic means for stopping said handling cables and unidirectionally holding same against motion consist of a stationary stop means limiting the strain of said spring-like member under maximum stress.

Claim 10

A device according to claim 1, wherein each cable controlling the relative outward extension of said second ramp section is connected to a self-acting winding-up appliance forming said self-acting tensioning and slack taking-up means whereas said automatic means for stopping said handling cable and unidirectionally holding samd against motion consist of a stationary fastening means for the end of said cable on said appliance.

Claim 11

A device according to claim 1, wherein each handling cable controlling the device outward extension of said second ramp section is connected to an automatic winding-up appliance forming said self-acting tensioning and slack taking-up means whereas said automatic means for stopping said cable and unidirectionally holding same against motion consist of braking means for braking said appliance at the end of the useful paying out motion.

Claim 12

A device according to claim 2, wherein each handling cable controlling the relative outward extension of said second ramp section is connected to a power-operated winch providing for constant cable tensioning and which is located on said vehicle to form one aforesaid load transfer means.

Claim 13

A device according to claim 2, wherein said load transfer means consist of at least one counterweight having a selectively adjustable weight and located on a lever arm integral with said second ramp section so as to urge the Latter towards its rasied outward extended position.

Claim 14

A device according to claim 1, comprising a third or outermost ramp section forming a supporting pad to bear on said outside platform and pivotally connected with an intermediate point thereof to the corresponding outer end of said second ramp section forming now an intermediate ramp section, said device comprising operated means for raising said outermost ramp section.

Claim 15

A device according to claim 13, wherein each handling cable controlling the extension of said intermediate ramp section is reeved over at least one associated loose main guide pulley carried by said intermediate ramp section and said cable is secured with its outer end to said outermost ramp section at a point located outwards beyond the pivotal connection of the latter with said intermediate ramp section to form said operated raising means.

Claim 16

A device according to claim 13, wherein at least one ram-like pressure fluid operated actuator is provided between said intermedate and outermost ramp sections to form said operated raising means.

Claim 17

A device according to claim 1, wherein one of said first and second ramp sections extends beyond its pivotal connection with the other ramp section with at least one longitudinal projecting integral boom carrying towards its free end at least one auxiliary guide pulley for each handling cable controlling the relative outward extension of said second ramp section and each cable for operating said first ramp section is reeved over several elevated auxiliary guide pulleys mounted in a same pulley block provided on said vehicle and on a plurality of main guide pulleys mounted in a same pulley block carried by said innermost or first ramp section, so as to form a reeving whereas each handling cable is reeved over several guide pulleys mounted on two pulley blocks, respectively, carried by each projecting boom, respectively, and by said other ramp section so as to form a reeving.

Claim 18

A device according to claim 16, wherein said second ramp section extends beyond its pivotal connection with said innermost or first ramp section with at least one integral projecting longitudinal boom carrying towards its free end each aforesaid main guide pulley whereas said innermost ramp section carries at least one auxiliary guide pulley for each handling cable controlling the relative outward extension of said second ramp section and leading from each main guide pulley.

Claim 19

A device according to claim 1, comprising automatic control means for keeping said innermost ramp section spaced from said platform in its lowered working position, each handling winch being phase-locked in follow-up relationship to said control means which consist of at least one sensor member secured to one of said first and second ramp sections adjacent to their pivotal connection and adapted to bear upon said platform for detecting any variation in the difference between the levels of said vehicle and said platform.

Claim 20

A device according to claim 1, comprising automatic control means for adjusting the relative angular positions of said first and second ramp sections to keep same in substantially aligned registering relationship or at an optimum slope, each handling winch being phase-locked in follow-up relationship to said control means which consist of at least one sensor member mounted on one of said ramp sections in the vicinity of its pivotal connection with the other ramp section, said sensor member being adapted to engage said other ramp section so as to measure the angle formed therebetween in particular during any upward motion of said vehicle.

Claim 21

A device according to claim 7, comprising automatic control means for adjusting the bearing reaction of said ramp onto said platfrom, each aforesaid load transfer means being phase-locked in follow-up relationship to said control means which consist of at least one pressured-detecting sensor member mounted on said ramp towards its outer end for bearing upon said platform in the working posItion of said ramp and for measuring said bearing reaction.

Claim 22

A device according to claim 1, comprising push ram means mounted on said vehicle and adapted to freely engage said innermost ramp section in its raised position to initiate its downward swinging motion through gravity and to brake or slow down its upward swinging motion at the end thereof, abutment and rest means being provided on said vehicle and engageable by said ramp in its raised and stowed position.

Claim 23

A device according to claim 1, wherein said innermost ramp section is provided with a pair of side frame members at least one of which carries a buttressing ram the line of action of which is spaced from the geometrical axis of pivotal connection between said adjacent innermost and second ramp sections, said buttressing ram being adapted to bear removably against an abutment means intergral with the corresponding side of said adjacent ramp section in the lowered and extended working position of said ramp for blocking said pivotal connection in the direction of rotation of increasing extension of the ramp, in a relative angular position which is selectively variable through the adjustable operative length of stroke of said ram, whereas selectively variable connecting means are provided between said side frame member and said corresponding side, respectively, of both ramp sections for blocking said pivotal connection in the direction of rotation of folding back said ramp, in the same relative angular position, and wherein on the one hand said ram is of the double-acting kind and pivotally connected with its body onto said side frame member of said innermost ramp section while extending in substantially parallel relation to the longtiudinal relative vertical plane of said side frame member, said ram being located higher than the geometrical axis of said pivotal connection between both ramp sections in their working position and said adjacent second ramp section also comprising a pair of side frame members on its opposite sides, respectively, whereas on the other hand said ram is provided with a movable push head adapted to freely and directly engage at least one substantially concave abutment pad forming said abutment means and secured to the adjacent end of said corresponding side frame member of said second ramp section; operated locking means being provided on said corresponding side frame member of said adjacent second ramp section to rigidly connect said movable push head with said abutment pad thereby to form said selectively variable connecting means.

Claim 24

A device according to claim 22, wherein said movable push head of said ram comprises at least one sidewise projecting portion adapted to engage said abutment pad; said abutment pad being substantially square shaped and said locking means comprising at least one movable retaining member actuated by an associated actuator and mounted on said adjacent second ramp section, said retaining member being adapted to bear against said sidewise projecting portion to keep same in engagement with said abutment pad.

Claim 25

A device according to claim 23, wherein each retaining member is automatically urged constantly towards its operative locking position by a resilient biasing means or through gravity so that its associated actuator is only used for unlocking purposes.

Claim 26

A device according to claim 22, wherein said retaining member consists of at least one arm adapted to swing in a plane substantially at right angles to said sidewise projecting portion and to be lowered into engagement with said sidewise projecting portion on that surface portion thereof which is opposite from said abutment pad to hold said sidewise projecting portion against motion, said swinging arm being on the other hand adapted to be swung upwards and away from said sidewise projecting portion to release same, said arm being engageable with said sidewise projecting portion through the tip of its free end portion, said tip having a mating shape which is complementary of that of thE lateral surface of said sidewise projecting portion.

Claim 27

A device according to claim 25, wherein said movable push head of said ram comprises a pair of transversely opposite and coaxially aligned thrust pins forming said sidewise projecting portions and adapted to co-operate with a pair of corresponding associated transversely spaced abutment pads whereas said retaining member is a fork-shaped part of the legs of which form locking arms spaced from each other according to the spacing between said abutment pads, said fork-shaped part being rotatably mounted on a transverse shaft fitted on said adjacent second ramp section, said fork-shaped part being connected through a radial crank arm to an auxiliary linear-displacement type pressure fluid operated actuator mounted on said adjacent second ramp section for rotating said fork-shaped part.

Claim 28

A device according to claim 22, comprising automatic safety means for avoiding any wrong operation and rendering the device fail-safe, said means being mounted on said adjacent second ramp section and adapted to check and to report the relative position of said locking means at the ends of the locking and unlocking strokes, respectively.

Claim 29

A device according to claim 22, comprising self-acting means for controlling the relative position of said movable push head of said ram, at the end of its stroke, against each abutment pad, said means consisting of at least one proximity detector which is phase-locked in follow-up relationship to means operating said locking means.

Claim 30

A device according to claim 22, comprising means for detecting the maximum motion of outward extension of both aforesaid successive ramp sections into their substantially aligned registering position and accordingly the end of maximum retraction stroke of said ram, said ram comprising inner mechanical stop means and said detecting means being adapted to discontinue the energizing of said ram.

Claim 31

A device according to claim 25, comprising by means for forced guiding of the movable push head of said ram, said means consisting of each sidewise projecting portion which is of elongated shape so as to project sidewise beyond said associated abutment pad and engage a guide slot carried by an associated supporting structure integral with the side frame member of said innermost ramp section.