Non-jamming self-adjust pawl and ratchet mechanism

A parking brake system of the self-adjust type for automatically removing slack from a parking brake cable, comprising:

• (a) a housing (6, 106, 206);
• (b) an operating lever (2, 102, 202) pivotally connected with said housing for movement between brake-released and brake-engaged positions;
• (c) means (28,30;
• 180,188;
• 280,288) for releasably maintaining said lever in said brake-engaged position relative to said housing;
• and
• (d) self-adjust means for releasably connecting said cable with said lever so that cable tension is progressively increased as said lever is pivoted in the brake-applying direction, including:
• (1) a cable track member (12, 112, 212) rotatably connected with said housing, said cable track member being adapted for connection with one end of the parking brake cable;
• (2) an adjuster ratchet (14, 114, 214) connected with said cable track member said adjuster ratchet having a plurality of ratchet teeth;
• (3) an adjuster pawl (18, 118, 218) pivotally connected with said lever, said adjuster pawl having a pawl tooth adapted for engagement with corresponding teeth on said ratchet in one of full engagement, partial tip-to-tip engagement, and non-load bearing top-on-top conditions, respectively;
• (4) adjuster spring means (16, 116, 216) normally rotatably biasing said cable track member in the cable-slack-removing direction relative to said housing;
• (5) cam-out means (44, 144, 47) mounted on said housing for pivoting said adjuster pawl to disengage the tooth thereof from said adjuster ratchet teeth when said operating lever is in the brake-disengaged position;
• and
• (6) cam-in means (46, 146;
• 47, 218c) for pivoting said adjuster pawl toward a fully-engaged position relative to said adjuster ratchet, said cam-in means being spaced from said cam-out means a distance greater than the distance between said cam-out means and the point of travel T.sub.4 of said lever at which the force vector (V.sub.c) produced by the progressively increasing cable tension exceeds the sum of the opposing adjuster spring force (V.sub.as) and the pedal force (V.sub.p), thereby to effect slight displacement of said adjuster pawl relative to said adjuster ratchet, whereby the occurrence of a tip-on-tip condition at the time of cam-in operation is prevented.