Torque-limiting spindle

1 . A torque-limiting spindle, comprising:

an input member extending along a longitudinal axis and configured for connection with a handle, the input member comprising an input member end face that varies longitudinally to thereby define a first engagement feature;

an output member extending along the longitudinal axis and configured for connection with a rotatable member of a lockset, the output member comprising an output member end face that varies longitudinally to thereby define a second engagement feature;

a bias mechanism engaged between the input member and the output member and exerting a biasing force to bias the input member toward the output member and urge the first engagement feature and the second engagement feature into engagement with one another; and

a clutch mechanism comprising the first engagement feature and the second engagement feature;

wherein the clutch mechanism is configured to transmit an input torque from the input member to the output member when the input torque is below a threshold torque; and

wherein the clutch mechanism is configured to slip by causing relative longitudinal movement of the input member and the output member when the input torque is above the threshold torque.

2 . The torque-limiting spindle of claim 1 , wherein the first engagement feature comprises a first longitudinal ramp;

wherein the second engagement feature comprises a second longitudinal ramp; and

wherein the first longitudinal ramp and the second longitudinal ramp are configured to urge one another longitudinally away from one another in response to the input torque.

3 . The torque-limiting spindle of claim 2 , wherein the first longitudinal ramp at least partially defines a first projection and a first recess;

wherein the second longitudinal ramp at least partially defines a second projection and a second recess;

wherein the first recess is operable to receive the second projection; and

wherein the second recess is operable to receive the first projection.

4 . The torque-limiting spindle of claim 1 , wherein the first engagement feature comprises a plurality of first projections and a plurality of first recesses;

wherein the second engagement feature comprises a plurality of second projections and a plurality of second recesses;

wherein the first recesses are operable to receive the second projections; and

wherein the second recesses are operable to receive the first projections.

5 . The torque-limiting spindle of claim 1 , wherein the bias mechanism comprises an external bias mechanism positioned externally of the input member and the output member and providing the biasing force urging the first engagement feature and the second engagement feature into engagement with one another.

6 . A lockset comprising the torque-limiting spindle of claim 1 , the lockset further comprising:

a bolt member engaged with the output member such that the bolt member is operable to move between an extended position and a retracted position in response to rotation of the output member; and

a handle rotationally coupled with the input member.

7 . The torque-limiting spindle of claim 1 , wherein the bias mechanism comprises:

an elongate member extending from the output member; and

a spring engaged between a first portion of the elongate member and a second portion of the input member.

8 . A torque-limiting spindle, comprising:

a first spindle member extending along a longitudinal axis, the first spindle member comprising a first end face that varies longitudinally to thereby define a first engagement feature;

a second spindle member extending along the longitudinal axis, the second spindle member comprising a second end face that varies longitudinally to thereby define a second engagement feature;

a bias mechanism engaged between the first spindle member and the second spindle member and exerting a biasing force to bias the first spindle member toward the second spindle member and urge the first engagement feature and the second engagement feature into engagement with one another; and

a clutch mechanism comprising the first engagement feature and the second engagement feature;

wherein the clutch mechanism is configured to transmit an input torque from the input member to the output member when the input torque is below a threshold torque; and

wherein the clutch mechanism is configured to slip by causing relative longitudinal movement of the input member and the output member when the input torque is above the threshold torque.

9 . The torque-limiting spindle of claim 8 , wherein the first spindle member comprises a chamber and a shoulder partially defining the chamber; and

wherein the bias mechanism comprises:

an elongate member comprising a head and an end portion opposite the head, wherein the end portion is engaged with the second spindle member; and

a spring disposed within the chamber and captured between the head and the shoulder.

10 . The torque-limiting spindle of claim 9 , wherein the end portion is threadedly engaged with the second spindle member such that rotation of the elongate member relative to the second spindle member adjusts the biasing force exerted by the spring.

11 . The torque-limiting spindle of claim 10 , wherein the head is disposed within the chamber; and

wherein the chamber has an open end through which the head is accessible to thereby facilitate rotation of the elongate member.

12 . The torque-limiting spindle of claim 11 , wherein the first spindle member further comprises one or more radial projections that project into the open end to thereby prevent removal of the elongate member from the chamber.

13 . A lockset comprising the torque-limiting spindle of claim 8 , the lockset further comprising:

a bolt member engaged with one of the first spindle member or the second spindle member such that the bolt member moves between an extended position and a retracted position in response to rotation of the one of the first spindle member or the second spindle member; and

a handle rotationally coupled with the other of the first spindle member or the second spindle member.

14 . The torque-limiting spindle of claim 8 , wherein the bias mechanism comprises:

an elongate member extending from the first spindle member; and

a spring engaged between a first portion of the elongate member and a second portion of the second spindle member.

15 . A torque-limiting spindle, comprising:

a first spindle member extending along a longitudinal axis, the first spindle member comprising a first longitudinal ramp;

a second spindle member extending along the longitudinal axis, the second spindle member comprising a second longitudinal ramp; and

a bias mechanism engaged between the first spindle member and the second spindle member and exerting a biasing force to bias the first spindle member toward the second spindle member and urge the first spindle member and the second spindle member into engagement with one another; and

wherein the first longitudinal ramp and the second longitudinal ramp are configured to engage one another in response to an input torque, to transmit the input torque between the first spindle member and the second spindle member when the input torque is less than a threshold torque, and to cause relative longitudinal movement of the first spindle member and the second spindle member when the input torque is greater than the threshold torque.

16 . The torque-limiting spindle of claim 15 , wherein the first spindle member comprises a first end face comprising the first longitudinal ramp; and

wherein the second spindle member comprises a second end face comprising the second longitudinal ramp.

17 . The torque-limiting spindle of claim 16 , wherein the first end face further comprises:

a first projection; and

a first recess that is longitudinally offset from the first projection and connected to the first projection by the first longitudinal ramp; and

wherein the second end face further comprises:

a second projection; and

a second recess that is longitudinally offset from the second projection and connected to the second projection by the second longitudinal ramp.

18 . The torque-limiting spindle of claim 15 , wherein the bias mechanism comprises a spring and an elongate member, the elongate member extending from the second spindle member into a chamber of the first spindle member; and

wherein the spring is disposed within the chamber and captured between a head of the elongate member and a shoulder of the first spindle member.

19 . The torque-limiting spindle of claim 15 , wherein the first spindle member comprises a chamber and a shoulder partially defining the chamber;

wherein the bias mechanism comprises a spring and an elongate member;

wherein the elongate member comprises:

a bolt having a threaded portion engaged with the second spindle member; and

a head; and

wherein the spring is disposed within the chamber and captured between the head and the shoulder.

20 . The torque-limiting spindle of claim 19 , wherein rotation of the bolt relative to the second spindle member adjusts the biasing force exerted by the spring;

wherein the head is disposed within the chamber; and

wherein the chamber has an open end through which the head is accessible to thereby facilitate rotation of the bolt.

21 . The torque-limiting spindle of claim 20 , wherein the first spindle member further comprises one or more radial projections that project into the open end to thereby prevent removal of the bolt from the chamber.

22 . A lockset comprising the torque-limiting spindle of claim 15 , the lockset further comprising:

a bolt member engaged with one of the first spindle member or the second spindle member such that the bolt member moves between an extended position and a retracted position in response to rotation of the one of the first spindle member or the second spindle member; and

a handle rotationally coupled with the other of the first spindle member or the second spindle member.

23 . The torque-limiting spindle of claim 15 , wherein the bias mechanism comprises:

an elongate member extending from the first spindle member; and

a spring engaged between a first portion of the elongate member and a second portion of the second spindle member.