Positive lock for height adjustable ambulance cot

1. A height adjustable ambulance cot comprising:

an upper frame providing at least one channeled support member having a plurality of holes, said at least one channeled support member having inner surfaces which comprise an upper track portion and a lower track portion;

a support mechanism configured to height adjust said upper frame;

a traverse frame member pivotably connected to the support mechanism;

at least one latching trolley configured for movement about said at least one channeled support member, said at least one latching trolley being connected to said traverse frame member, said at least one latching trolley comprising upper and lower rollers, wherein in a weighted position, said upper rollers engage said upper track portion, and in an unweighted position, said lower rollers engage a lower track portion of said at least one channeled support member; and

a positive lock having at least one locking pin configured to be held releaseably in said plurality of holes via an interference fit in said weighted position, wherein said interference fit is cleared by lifting said upper frame to said unweighted position, thereby permitting said at least one locking pin to be released from an engaged one of said plurality of holes.

2. The height adjustable ambulance cot according to claim 1 , wherein said at least one locking pin is released from the engaged one of said plurality of holes via an actuator upon clearing said interference fit by lifting said upper frame.

3. The height adjustable ambulance cot according to claim 1 , wherein said positive lock further includes a pivoting arm mounted pivotably to said traverse frame member, said pivoting arm is configured to move said at least one locking pin via operation of an actuator upon clearing said interference fit by lifting said upper frame.

4. The height adjustable ambulance cot according to claim 1 , wherein said positive lock further includes a pivoting arm mounted pivotably to said traverse frame member and connected to an actuator via a spring, said spring having a spring constant that is insufficient to overcome said interference fit, and wherein said pivoting arm is configured to move said at least one locking pin via operation of said actuator upon clearing said interference fit by lifting said upper frame.

5. The height adjustable ambulance cot according to claim 1 , further comprising an extendable handle bar frame member, wherein said at least one locking pin is released from the engaged one of said plurality of holes via an actuator, mounted on said extendable handle bar frame member, upon clearing said interference fit by lifting said upper frame.

6. The height adjustable ambulance cot according to claim 1 , further comprising an extendable bent U-shape handle bar frame member, wherein said at least one locking pin is released from the engaged one of said plurality of holes via an actuator, mounted on said extendable handle bar frame member, upon clearing said interference fit by lifting said upper frame.

7. The height adjustable ambulance cot according to claim 1 , further comprising an extendable handle bar frame member, wherein said at least one locking pin is released from the engaged one of said plurality of holes via an actuator, mounted on said extendable handle bar frame member, upon clearing said interference fit by lifting said upper frame, and wherein said cot further comprises a handle bar locking device having a pair of actuators each connected to a respective one of a pair of spring biased pinning rods normally accommodated within a respective hole provided through said upper frame and at least partially into said handle bar frame member.

8. The height adjustable ambulance cot according to claim 1 , wherein said at least one locking pin is spring biased and accommodated slidably within said traverse frame member.

9. The height adjustable ambulance cot according to claim 1 , further comprising a hand operated actuator operatively connected to said positive lock via a pull cable connected to a spring of said positive lock, said positive lock further includes a pivoting arm mounted pivotably to said traverse frame member and connected to said spring, and an at least one pull member connected pivotably to said pivoting arm and said at least one locking pin.

10. The height adjustable ambulance cot according to claim 1 , wherein the inner surfaces of said at least one channeled support member define a c-shape.

11. A method of adjusting height of an emergency cot according to claim 1 , said method comprising:

lifting said upper frame to clear said at least one locking pin of said interference fit;

operating an actuator provided to said cot to release said at least one locking pin from an engaged one of said plurality of holes; and

repositioning said traverse frame member about said at least one channeled support to height adjust said cot.

12. The method according to claim 11 wherein operating said actuator releases said at least one locking pin from the engaged one of said plurality of holes via pivoting of a pivoting arm from a pull of a pull cable and spring connected between said actuator and said pivoting arm, said pivoting arm being operatively connected to said at least one locking pin.

13. A height adjustable ambulance cot comprising:

an upper frame providing at least one channeled support member having a plurality of holes, said at least one channeled support member having inner surfaces which comprise an upper track portion and a lower track portion;

a lower frame providing castor wheels;

a support mechanism connected between said upper and lower frames and configured to height adjust said upper frame relative to said lower frame;

a traverse frame member pivotably connected to said support mechanism;

at least one latching trolley configured for movement about said at least one channeled support member, said at least one latching trolley being connected to said traverse frame member, said at least one latching trolley comprising upper and lower rollers, wherein in a weighted position, said upper rollers engage said upper track portion, and in an unweighted position, said lower rollers engage a lower track portion of said at least one channeled support member; and

a positive lock having at least one locking pin configured to be held releaseably in said plurality of holes via an interference fit in said weighted position, a pivoting arm mounted pivotably to said traverse frame member and connected to an actuator via a spring, said spring having a spring constant that is insufficient to overcome said interference fit, wherein said pivoting arm is configured to move said at least one locking pin from an engaged one of said plurality of holes via operation of said actuator upon clearing said interference fit, wherein said interference fit is cleared by lifting said upper frame to said unweighted position.

14. The height adjustable ambulance cot according to claim 13 , further comprising an extendable handle bar frame member, wherein said at least one locking pin is released from the engaged one of said plurality of holes via said actuator, mounted on said extendable handle bar frame member, upon clearing said interference fit by lifting said upper frame.

15. The height adjustable ambulance cot according to claim 13 , further comprising an extendable bent U-shape handle bar frame member, wherein said at least one locking pin is released from the engaged one of said plurality of holes via said actuator, mounted on said extendable handle bar frame member, upon clearing said interference fit by lifting said upper frame.

16. The height adjustable ambulance cot according to claim 13 , further comprising an extendable handle bar frame member, wherein said at least one locking pin is released from the engaged one of said plurality of holes said an actuator, mounted on said extendable handle bar frame member, upon clearing said interference fit by lifting said upper frame, and wherein said cot further comprises a handle bar locking device having a pair of actuators each connected to a respective one of a pair of spring biased pinning rods normally accommodated within a respective hole provided through said upper frame and at least partially into said handle bar frame member.

17. The height adjustable ambulance cot according to claim 13 , wherein said at least one locking pin is spring biased and accommodated slidably within said traverse frame member.

18. The height adjustable ambulance cot according to claim 13 , wherein said actuator is a hand operated actuator operatively connected to said positive lock via a pull cable connected to said spring of said positive lock, said positive lock further includes a pivoting arm mounted pivotably to said traverse frame member and connected to said spring, and an at least one pull member connected pivotably to said pivoting arm and said at least one locking pin.

19. The height adjustable ambulance cot according to claim 13 , wherein the inner surfaces of said at least one channeled support member define a c-shape.

20. The height adjustable ambulance cot according to claim 13 , comprising a light indicator configured to illuminate when said at least one locking pin is disengaged from said plurality of holes.