Mobile roof safety device

1. A mobile roof safety device for use on substantially flat roofs for the safety of workers, said roof safety device comprising:

a displaceable frame having a weighted base adapted to be positioned on a flat roof surface, said weighted base having opposed top and bottom surfaces,

retractable wheel assemblies secured to said frame for displacing said frame on said flat roof surface with said bottom surface of said weighted base elevated therefrom, wherein said wheel assemblies each comprise:

pivotal wheel support arms pivotally engaged to the frame and supporting one or more wheels, and

a jack pivotally engaged to the pivotal wheel support arms and pivotally engaged to the frame above and spaced apart from said top surface of said weighted base, said jack displacing said pivotal wheel support arms between a first position where said or more wheels protrude below said bottom surface of said weighted base to engage said flat roof surface and a second position where said or more wheels are above a plane defined by said bottom surface of said weighted base,

at least one actuable roof surface gripping assembly secured in a lower portion of said frame above said bottom surface of said weighted base, said actuable roof surface gripping assembly being biased in a disengaged position , said roof surface gripping assembly in the disengaged position being disposed spaced above said plane defined by said bottom surface of said weighted base, and

a safety line secured to said roof surface gripping assembly,

wherein when a pulling force is applied to said safety line by a worker secured thereto falling off said roof, said roof surface gripping assembly moves away from the disengaged position and to an engaged position where part of the gripping assembly protrudes below said plane defined by said bottom surface of said weighted base,

wherein with said wheel assemblies in the second position, said gripping assembly in the engaged position engages said flat roof surface adjacent said weighted base to arrest said worker secured to said safety line with the weight of said weighted base providing additional restraint against said pulling force on said safety line, and

wherein one of said wheel assemblies is a front wheel assembly having a pivotal displacement low arm pivotally secured at a fork end to said wheel support arms, on a pivot axis, said one or more wheels including a front wheels secured between said wheel support arms, said pivot axis spaced above a wheel axis of said front wheel, said fork end engaging a tire of said wheel when said pivotal displacement arm is positioned at a predetermined forward and downward angle to constitute a brake for said wheel.

2. A movable safety device as claimed in claim 1 wherein said weighted base is a solid metal plate having a flat bottom surface, said roof surface gripping assembly being secured to a top surface of said solid metal plate adjacent a side edge thereof, said solid metal plate having a predetermined weight creating a dead load.

3. A movable safety device as claimed in claim 2 further comprising an additional roof surface gripping assembly, the roof surface gripping assemblies being spaced-apart from one another, said side edge of said solid metal plate having recesses therein for accommodating each surface gripping assembly.

4. A movable safety device as claimed in claim 1 wherein said actuable roof surface gripping assembly comprises a pivoting arm secured to a pivot connection, a gripping formation at a lower end portion of said pivoting arm, said safety line being secured to said pivoting arm above said pivot connection.

5. A movable safety device as claimed in claim 4 wherein said pivoting arm is pivotally secured above a top wall of said weighted base adjacent a side edge thereof, said roof surface gripping assembly being biased in the disengaged position by a helical spring secured to a top end portion of said pivoting arm and to said top wall of said solid metal plate.

6. A movable safety device as claimed in claim 4 wherein said gripping formation includes a gripping plate having a claw edge formed of pointed teeth, said gripping plate being secured to said lower end portion of said pivoting arm and disposed at a downward angle towards said flat roof surface.

7. A movable safety device as claimed in claim 4 wherein said gripping formation includes a first gripping plate having a claw edge formed of pointed teeth, said first gripping plate being secured to said lower end portion of said pivoting arm and disposed at a downward angle, and a second gripping plate secured to said lower end portion of said pivoting arm above said first gripping plate and extending substantially co-extensively with said pivoting arm, said second gripping plate also having a claw edge.

8. A movable safety device as claimed in claim 7 wherein a bridge arm is secured over said second gripping plate and secured above a recess accommodating said gripping assembly to protect said safety line from said claw edge of said second gripping plate.

9. A movable safety device as claimed in claim 4 wherein said safety line comprises an energy absorbing locking mechanism which is actuated by a predetermined load, said safety line being attached to a metal attachment ring secured to said pivoting arm.

10. A movable safety device as claimed in claim 1 wherein there is further provided safety line connection means immovably secured to said displaceable frame for the connection of safety lines of predetermined lengths relative to a restrained work zone delineated adjacent said mobile roof safety device and spaced from peripheral edges of said flat roof surface.

11. A movable safety device as claimed in claim 1 wherein said jack is a hand operable jack having an extendible and retractable telescopic shaft secured at a bottom end to said wheel support arms, and a crank to displace said telescopic shaft.

12. A movable safety device as claimed in claim 2 wherein there is further provided an angle indicator secured to said solid metal plate adjacent said side edge and in relation to said actuable roof surface gripping assembly to indicate a safe working zone for said worker secured to said actuable surface gripping assembly by said safety line.

13. A mobile roof safety device for use on substantially flat roofs for the safety of workers, said roof safety device comprising:

a displaceable frame having a weighted base adapted to be positioned on a flat roof surface, said weighted base having a bottom surface,

retractable wheel assemblies secured to said frame for displacing said frame on said flat roof surface with said bottom surface of said weighted base elevated therefrom, said wheel assemblies secured to said frame, said wheel assemblies each comprising pivotal wheel support arms for supporting one or more wheels, said pivotal wheel support arms being displaceable to position said one or more wheels at a retracted position to lower said weighted base on said flat roof surface with said wheels spaced thereabove, and to an engaged position where said wheels are displaced below said bottom surface of said weighted base,

at least one actuable roof surface gripping assembly secured in a lower portion of said frame above said weighted base, said actuable roof surface gripping assembly being biased in a disengaged position, said roof surface gripping assembly in the disengaged position being disposed spaced above a plane defined by said bottom surface of said weighted base, and

a safety line secured to said roof surface gripping assembly,

wherein when a pulling force is applied to said safety line by a worker secured thereto falling off said roof, said roof surface gripping assembly moves away from the disengaged position and to an engaged position where part of the gripping assembly protrudes below said plane defined by said bottom surface of said weighted base,

wherein with the retractable wheel assemblies retracted such that said bottom surface of said weighted base rests against said flat roof surface, said gripping assembly in the engaged position engages said flat roof surface adjacent said weighted base to arrest said worker secured to said safety line with the weight of said weighted base providing additional restraint against said pulling force on said safety line,

wherein one of said wheel assemblies is a front wheel assembly having a pivotal displacement tow arm pivotally secured at a fork end to said wheel support arms on a pivot axis, said one or more wheels including a front wheels secured between said wheel support arms, said pivot axis spaced above a wheel axis of said front wheel, said fork end engaging a tire of said wheel when said pivotal displacement arm is positioned at a predetermined forward and downward angle to constitute a brake for said wheel.

14. A movable safety device as claimed in claim 13 wherein said weighted base is a solid metal plate having a flat bottom surface, said roof surface gripping assembly being secured to a top surface of said solid metal plate adjacent a side edge thereof, said solid metal plate having a predetermined weight creating a dead load.

15. A movable safety device as claimed in claim 14 wherein there is further provided an angle indicator secured to said solid metal plate adjacent said side edge and in relation to said actuable roof surface gripping assembly to indicate a safe working zone for said worker secured to said actuable surface gripping assembly by said safety line.

16. A movable safety device as claimed in claim 14 further comprising an additional roof surface gripping assembly, the roof surface gripping assemblies being spaced-apart from one another, said side edge of said solid metal plate having recesses therein for accommodating each surface gripping assembly.

17. A movable safety device as claimed in claim 13 wherein said actuable roof surface gripping assembly comprises a pivoting arm secured to a pivot connection, a gripping formation at a lower end portion of said pivoting arm, said safety line being secured to said pivoting arm above said pivot connection.

18. A movable safety device as claimed in claim 17 wherein said pivoting arm is pivotally secured above a top wall of said weighted base adjacent a side edge thereof, said roof surface gripping assembly being biased in the disengaged position by a spring secured to a top end portion of said pivoting arm and to said top wall of said solid metal plate.

19. A movable safety device as claimed in claim 17 wherein said gripping formation includes a first gripping plate having a claw edge formed of pointed teeth, said first gripping plate being secured to said lower end portion of said pivoting arm and disposed at a downward angle, and a second gripping plate secured to said lower end portion of said pivoting arm above said first gripping plate and extending substantially co-extensively with said pivoting arm, said second gripping plate also having a claw edge.

20. A movable safety device as claimed in claim 19 wherein a bridge arm is secured over said second gripping plate and secured above a recess accommodating said gripping assembly to protect said safety line from said claw edge of said second gripping plate.