Rail plate retainer for use with rail tie exchanger

1. A plate retainer apparatus for use on a railroad track with a tie exchanger having a main frame, said apparatus configured for gripping and retaining rail tie plates to a rail during a rail tie exchange process, comprising:

a plate retainer workhead constructed and arranged for movement independent of that of the main frame;

said workhead including a pair of workhead modules, each said module associated with a rail of the track and configured for retaining a single tie plate associated with a target tie at a time, wherein each said module has at least one jaw arm pivotally moving between a travel position and a work position, each said jaw arm having at least two jaws pivotally mounted to each said jaw arm, wherein said at least two jaws each move between an open position and a closed position; and

each said workhead module being independently movable relative to the main frame and independently of each other.

2. The plate retainer apparatus of claim 1 wherein said modules are hingedly connected to each other.

3. The plate retainer apparatus of claim 2 , wherein said modules are connected to each other by pairs of hinge plates located on a forward and rear side of the target tie.

4. The plate retainer apparatus of claim 1 , further including fluid power cylinders connecting each said module to the main frame.

5. The plate retainer apparatus of claim 1 further including guide wheels on each said module for engaging a respective rail.

6. The plate retainer apparatus of claim 1 further including a lock on said module for releasably retaining said jaw arm in the travel position.

7. The plate retainer apparatus of claim 1 further including four jaws associated with each target rail plate.

8. The plate retainer apparatus of claim 1 , each said jaw having meshing teeth along complementary edges.

9. The plate retainer apparatus of claim 8 , further including a fluid powered cylinder mounted to each pair of jaws for moving said jaws between an open and a closed position.

10. The plate retainer apparatus of claim 8 , further including a plate engaging surface on each said jaw including a convex plate engaging surface, and a depending plate edge-engaging tab.

11. A plate retaining workhead for use with a rail tie exchanger, said workhead comprising:

at least one workhead module, each said module including an arm pivoting between a travel position and a work position;

each said arm having at least one pair of associated jaws pivotally mounted for movement between an open position and a closed position, said jaws each having a pivot axis that is transverse to a longitudinal axis of said at least one workhead module and constructed and arranged for engaging forward and rear edges of a target tie plate;

a fluid power cylinder mounted to each said pair of jaws for moving said jaws between the open and closed position.

12. The plate retaining workhead of claim 11 , further including a lock on each said workhead module, constructed and arranged for releasably retaining said arm in the travel position.

13. The plate retaining workhead of claim 11 , further including four of said jaws associated with each target tie plate, two of said jaws engaging the plate on a field side of an associated rail, and two of said jaws engaging the plate on a gauge side of the rail.

14. The plate retaining workhead of claim 11 , wherein each said jaw has plate engaging surface on each said jaw including a convex plate engaging surface, and a depending plate edge-engaging tab.

15. The plate retaining workhead of claim 11 , further including guide wheels on each said module for engaging a respective rail.

16. A plate retainer apparatus for use on a railroad track with a tie exchanger having a main frame, said apparatus configured for gripping and retaining rail tie plates to a rail during a rail tie exchange process, comprising:

a plate retainer workhead constructed and arranged for movement independent of that of the main frame;

said workhead including a pair of workhead modules, each said module associated with a rail of the track and configured for retaining a single tie plate associated with a target tie at a time;

each said module having at least one jaw arm pivotally moving between a travel position and a work position, each said jaw arm including at least two jaws pivotally mounted to each said jaw arm, wherein said at least two jaws each move between an open position and a closed position; and

each said workhead module being movable relative to the main frame independently of each other.

17. A plate retainer apparatus for use on a railroad track with a tie exchanger having a main frame, said apparatus configured for gripping and retaining rail tie plates to a rail during a rail tie exchange process, comprising:

a plate retainer workhead constructed and arranged for movement independent of that of the main frame;

said workhead including a pair of workhead modules, each said module associated with a rail of the track and configured for retaining a single tie plate associated with a target tie at a time, each said module including at least one pair of jaws, wherein said at least one pair of jaws having meshing teeth along complementary edges, each said jaw including a convex plate engaging surface, and a depending plate edge-engaging tab; and

each said workhead module being independently movable relative to the main frame and independently of each other.