High load descender with adaptive release linkage
View Patent ↗A high load descender for rope access and rescue has a ratcheting sheave mounted to a pivoting arm, which translate with rope tension against a fixed shoe. The ratcheting sheave has a groove that grips rope during descent while allowing free rotation for ascent and progress capture. An adaptive release linkage enhances ease of operation and control while maintaining convenient handle position in a variety of conditions.
1. A descender for controlling descent of a user along a rope; the descender comprising:
a chassis with a first end of a pivot arm pivotably attached thereto, wherein a control ring and a control ring aperture are integrally formed into the chassis;
an opening plate movably attached to the chassis, the opening plate movable between an open and a closed position;
a generally circular sheave, the sheave having a circumference, the circumference including a groove;
the generally circular sheave rotatably attached directly to a second end of the pivot arm;
a guide and a shoe, each of the guide and the shoe attached to the chassis and positioned on substantially opposite sides of the sheave, the sheave positioned a variable distance between the guide and the shoe, such that when the opening plate is in the open position, the rope is installed by inserting the rope past the guide, around at least a substantial portion of the circumference of the sheave, and past the shoe, and when the opening plate is in the closed position, a path for the rope is formed such that when the rope is in the path during use the rope is caused to slide against the guide and the shoe, and the rope is selectively forced into the groove;
the second end of the pivot arm biased away from the shoe;
a handle engaged with the pivot arm, the handle configured to move to control adjusting the variable distance between the sheave and the shoe, the handle including a pawl having teeth and a tail;
a cam rotatably mounted to the chassis;
a cam spring forcing the cam toward a pivot arm roller;
the teeth selectively engaged with the cam;
the handle configured to rotate to a stowed position such that the tail contacts the control ring, which causes the pawl to rotate and disengage from the cam; and
an attachment hole passing through the chassis and the opening plate such that when the opening plate is in the closed position, an operator can lock the descender in the closed position by inserting an attachment through the attachment hole.
2. The descender of claim 1 , wherein the sheave can freely rotate in only one direction.
3. The descender of claim 1 , wherein the guide is a roller that can freely rotate.
4. The descender of claim 1 , wherein the shoe is a roller that can freely rotate.
5. The descender of claim 1 , wherein a spring biases the pivot arm away from the shoe.
6. The descender of claim 1 , further including a panic trigger pin that disengages the handle from the pivot arm, thereby resuming clamping force on the rope, if the handle is rotated past a predetermined point.
7. The descender of claim 1 , wherein the sheave does not rotate during descent, but can freely rotate during ascent.