Rescue hoist with cable release safety provision
A rescue hoist including a cable drum assembly generally including a cable drum having a cable groove and a recess positioned at one end of the cable groove, a shear pin extending transverse across the recess, and a cable assembly including a cable routed along the cable groove and a cable hook mounted to one end of the cable. In use, to secure the cable assembly to the cable drum, the cable hook is received in the recess and hooked around the shear pin according to a predefined installation sequence. In use, to provide a cable release provision, the shear pin includes spaced reduced diameter sections positioned on opposing lateral sides of the cable hook configured to shear in response to a load on the cable exceeding a predefined threshold load value.
1 . A cable drum assembly, comprising:
a cable drum having a cable groove and a recess positioned at one end of the cable groove;
a shear pin extending transverse across the recess; and
a cable assembly including a cable routed along the cable groove and a cable hook mounted to one end of the cable;
wherein:
to secure the cable assembly to the cable drum, the cable hook is received in the recess and hooked around the shear pin; and
to provide a cable release provision, the shear pin includes spaced reduced diameter sections positioned adjacent opposing lateral sides of the cable hook configured to shear in response to a load on the cable exceeding a predefined threshold load value.
2 . The cable drum assembly according to claim 1 , wherein the shear pin is removably received in an opening formed through one end of the cable drum.
3 . The cable drum assembly according to claim 2 , further comprising a shear pin retention mechanism comprising:
a retention plate positioned in a recess formed in the one end of the cable drum, the retention plate including a first portion for engaging against a head of the shear pin and a second portion defining spaced openings; and
threaded fasteners each configured to be received through one of the spaced openings and threadably engaged in the cable drum to secure the retention plate to the cable drum.
4 . The cable drum assembly according to claim 3 , wherein each of the threaded fasteners includes a head having at least one radial opening for receiving an anti-rotation cable for constraining rotation of the threaded fasteners.
5 . The cable drum assembly according to claim 2 , wherein:
the shear pin has an annular head having a tangential chamfer;
the recess formed in the one end of the cable drum has a linear end wall; and
when the shear pin is installed in the cable drum, the linear end wall interacts with the tangential chamfer to constrain rotational motion of the shear pin relative to the cable drum.
6 . The cable drum assembly according to claim 2 , further comprising spaced bushings mounted in the opening formed through the one end of the cable drum, wherein the shear pin is mounted in the spaced bushings.
7 . The cable drum assembly according to claim 1 , wherein the cable hook is swaged onto the one end of the cable.
8 . The cable drum assembly according to claim 1 , wherein the shear pin is positioned relative to the recess such that the cable hook is installable only in a direction opposite a winding direction of the cable around the cable drum.
9 . The cable drum assembly according to claim 1 , wherein the recess receiving the cable hook is configured to constrain lateral motion of the cable hook to maintain a position of the cable hook between the spaced reduced diameter sections of the shear pin.
10 . A cable release assembly, comprising:
a shear pin removably installable in a rotatable cable drum; and
a cable assembly including a cable and a cable hook mounted to one end of the cable;
wherein:
the cable hook is configured to be hooked around the shear pin; and
the shear pin includes spaced reduced diameter sections positioned on opposing lateral sides of the cable hook configured to shear in response to a load on the cable exceeding a predefined threshold load value.
11 . The cable release assembly according to claim 10 , wherein, when the cable hook is hooked around the shear pin, a longitudinal axis of the cable hook is orthogonal to a longitudinal axis of the shear pin.
12 . The cable release assembly according to claim 10 , wherein the shear pin is stainless steel.
13 . The cable release assembly according to claim 10 , wherein:
the shear pin is removably installed in the rotatable cable drum transverse to a recess,
the cable hook is positioned in the recess; and
the cable hook is laterally constrained in the recess such that pulling force on the cable is orthogonal to a longitudinal axis of the shear pin.
14 . A rescue hoist, comprising:
a rotatable cable drum;
a shear pin mounted in a recess formed in the rotatable cable drum; and
a cable assembly including a length of cable and a cable hook mounted to one end of the length of cable;
wherein:
the cable hook is configured to be received in the recess and hooked around the shear pin according to a predefined installation sequence in which the cable hook initially hooks onto the shear pin when the cable hook is oriented in a direction opposite a winding direction of the length of cable along the cable drum; and
the shear pin is configured to fracture to release the cable assembly from attachment to the cable drum when a load on the cable exceeds a predefined threshold load value.
15 . The rescue hoist according to claim 14 , wherein the shear pin is mounted transverse across the recess formed in the rotatable cable drum.
16 . The rescue hoist according to claim 14 , wherein the cable drum includes a helical groove defined by an upstanding helical rib.
17 . The rescue hoist according to claim 14 , wherein the cable assembly further comprises a hook mounted to an opposing end of the length of cable.
18 . The rescue hoist according to claim 14 , wherein the rescue hoist is adapted to be mounted to an aircraft under-wing and adjacent an opening in an airframe of the aircraft.
19 . The rescue hoist according to claim 14 , wherein the cable hook is swaged onto the one end of the length of cable.
20 . The rescue hoist according to claim 14 , wherein the predefined threshold load value is about 800 lbs.