Elevator car brake with shoes actuated by springs

Braking apparatus comprising:

• a first brake shoe mounted in a fixed position and having a braking surface;
• a second brake shoe at one side of said first brake shoe and having a braking surface facing, but spaced from, said braking surface of said first shoe, said second brake shoe being movable toward and away from said first shoe;
• cam surface means mounted in a fixed position at the side of said first shoe opposite from said one side, said cam surface means providing a pair of spaced cam surfaces which increase in spacing from said second shoe and which face away from said second shoe;
• a cam follower engaging said cam surfaces and movable in the direction from a lesser spacing of said cam surfaces from said second shoe to a larger spacing of said cam surfaces from said second shoe;
• a pair of links pivotally connected to said cam follower and to said second shoe for moving said second shoe toward said first shoe in response to movement of said cam follower;
• a pair of compressible springs intermediate said cam surfaces and pivotally connected to said cam follower and said second shoe for urging said cam follower in the direction in which it moves said second shoe toward said first shoe;
• a hydraulic piston and cylinder assembly intermediate said springs and connected to said cam follower for compressing said springs;
• and
• releasable locking means connected to said cam follower for locking said springs in the state thereof to which they are compressed by said hydraulic piston and cylinder assembly, said releasable locking means, upon release thereof, permitting said springs to move said cam follower and move said second shoe toward said first shoe.

In an elevator system comprising an elevator car, car guide means, car hoisting apparatus including car hoisting ropes and electrical means responsive to car movement, the improvement comprising braking apparatus comprising:

• a pair of brake shoes having facing surface faces one of said shoes being mounted for movement of its face toward the face of the other of said shoes, said brake shoes being engageable with one of said car guide means and said hoisting apparatus for arresting movement of said car;
• cam means connected to said one of said shoes for moving the face of said one of said shoes toward the face of the other of said shoes;
• compressible spring means connected to said cam means for actuating said cam means and thereby causing said face of said one of said shoes to move toward the face of the other of said shoes;
• compressing means connected to said spring means for compressing said spring means;
• and
• releasable locking means responsive to said electrical means and said spring means for holding said spring means in its compressed state after said spring means has been compressed by said compressing means;
• whereby upon abnormal movement of said car, said locking means is released and said spring means actuates said cam means and moves the face of said one of said shoes toward the face of the other of said shoes and causes said shoes to engage and grip said one of said car guide means and said hoisting apparatus.