Brake and control therefor

Claim 2

A braking apparatus including a brake actuator comprising a mechanical link for establishing braking and non-braking conditions in said braking apparatus, first means for biasing said link with a first braking force, second means for biasing said link with a second braking force, first means for connecting said first biasing means to said link; second means for connecting said second biasing means to said link and control means for controlling the displacement of said link so that said first and second biasing means apply said first and second breaking forces to said link at successive times under normal stop conditions and so that said first and said second biasing means apply said first and said second braking forces to said link at the same time under emergency stop conditions.

Claim 3

A braking apparatus according to claim 1 wherein said first biasing means includes a spring.

Claim 4

A braking apparatus according to claim 1 wherein said second biasing means includes a spring.

Claim 5

A braking apparatus according to claim 1 wherein said second means for connecting said second biasing means to said link includes a member upon which said second biasing means inposes said second braking force and which is movable with respect to said link and a limit on said link for limiting the movement of said member with respect to said link in the direction of said second braking force.

Claim 6

A braking apparatus as set forth in claim 1 wherein said control means includes a first solenoid for displacing said link to overcome said biasing means and establish said non-braking condition and for releasing said link to release said biasing means and establish said braking condition.

Claim 7

A braking apparatus as set forth in claim 5 wherein said control means includes a second solenoid for delaying the release of said second biasing means for a predetermined time after said firt solenoid releases said link under normal stop conditions.

Claim 8

A braking apparatus as set forth in claim 6 wherein said control means includes circuitry for preventing said second solenoid from delaying the release of said second biasing means under emergency stop conditions.

Claim 9

A braking apparatus as set forth in claim 1 wherein said control means includes means for displacing said link to establish said non-braking condition and maintaining means for preventing said second biasing means from applying said second braking force to said link.

Claim 10

A braking apparatus comprising a brake drum; a brake lever; a brake shoe attached to said brake lever; first application means for applying a first braking force to said brake lever; first release means for actuating said first application means; second application means for applying a second braking force to said brake lever; second release means for actuating said second application means; and control means for actuating said first and said second application means at successive times under normal stop conditions and for actuating said first and said second application means at the same time under emergency stop conditions.

Claim 11

A braking apparatus comprising a brake drum; a brake lever; a brake shoe attached to said brake lever; first application means for applying a first braking force to said brake lever; first release means for actuating said first application means; second application means for applying a second braking force to said brake lever; second release means for actuating said second application means; and control means for actuating said first and said second application means at successive times under normal stop conditions and for actuating said first and said second application means at the same time under emergency stop conditions.

Claim 12

A braking apparatus according to claim 9 wherein said control means includes time delay means for delaying actuation of said second release means under normal stop conditions.

Claim 13

A braking apparatus according to claim 8 wherein said mechanical link is a rod movable generally longitudinally between positions defining the braking and non-braking conditions, said first and second biasing means comprise respective first and second springs, said displacing means and said maintaining means comprise respective first and second solenoids, and said second means for connecting said second biasing means to said link is a member movable with respect to said link rod and a limit on said link for limiting the movement of said member with respect to said link in the biasing direction of said second biasing means.

Claim 14

A braking apparatus according to claim 11 wherein said second solenoid is generally coaxial with said rod, said member is an armAture for said second solenoid movable longitudinally on said rod, and said second spring is maintained under compression by said armature.

Claim 15

A braking apparatus according to claim 12 wherein said second solenoid has a core in which sufficient flux is developed to maintain said armature against said core in opposition to said second spring.

Claim 16

A braking apparatus comprising a brake drum, a brake support, first and second brake levers pivotally mounted on said brake support for inward and outward movement in relation to said drum, first and second brake shoes mounted on said first and second brake levers between said levers and said drum, a first solenoid having a first core and a first armature, said first core being fixedly attached to said first brake lever, a mechanical link having one end thereof fixedly attached to said second lever and having the other end thereof in contact with said first armature for inward and outward movement therewith, a plurality of elongated guide members fixedly attached to said first brake lever and having axes substantially parallel to said link, a second solenoid having a second core and a second armature, first and second link stops for limiting longitudinal movement along said link, first and second sets of guide steps for limiting longitudinal movement along said guide members, a first set of plates slidably mounted on said link and said guide members between said first link stop and said first set of guide stops, a first spring located between said first set of plates, said second core and said second armature being slidably mounted on said link and said guide members between said second link stop and said second set of guide stops, a second spring located between said second core and said second armature, a first coil for energizing said first core to compress said first and second springs when tHe braking apparatus is in a non-braking condition and to release at least one of said springs when the braking apparatus is in a braking condition, and a second coil for enegizing and de-energizing said second core to control the release of said second spring.

Claim 17

A braking apparatus comprising a brake drum, a brake support, first and second brake levers pivotally mounted on said brake support for inward and outward movement in relation to said drum, first and second brake shoes mounted on said first and second brake levers between said levers and said drum, a first solenoid having a first core and a first armature, said first core being fixedly attached to said first brake lever, a mechanical link having one end thereof fixedly attached to said second lever and having the other end thereof in contact with said first armature for inward and outward movement therewith, a plurality of elongated guide members fixedly attached to said first brake lever and having axes substantially parallel to said link, a second solenoid having a second core and a second armature, first and second link stops for limiting longitudinal movement along said link, first and second sets of guide steps for limiting longitudinal movement along said guide members, a first set of plates slidably mounted on said link and said guide members between said first link stop and said first set of guide stops, a first spring located between said first set of plates, said second core and said second armature being slidably mounted on said link and said guide members between said second link stop and said second set of guide stops, a second spring located between said second core and said second armature, a first coil for energizing said first core to compress said first and second springs when tHe braking apparatus is in a non-braking condition and to release at least one of said springs when the braking apparatus is in a braking condition, and a second coil for enegizing and de-energizing said second core to control the release of said second spring.