Claims
- 1. A drive system for moving a load along a curved path, said drive system comprising:a base for mounting said drive system, said base having a curved track for guiding said load along said curved path; a load engaging mechanism mounted on said base for movement relative to said base, said load engaging mechanism moving said load, said load engaging mechanism having a curved track engaging roller for engaging said curved track; a linear drive mechanism mounted on said base, said linear drive mechanism including a linearly driven member, a driving pivot, a pneumatic cylinder, a drive nut having a linear power connection to said cylinder, at least one of said cylinder and said drive nut being mounted on said base, said drive nut engaging a drive screw to be driven thereby, whereby said linear motion of said drive nut imparts rotation motion on said drive screw and hence said driving pivot; and a drive link attached to said driving pivot at a drive force receiving end of said drive link, said drive link including a driven pivot at a drive force communicating end of said drive link, said driven pivot being attached to said load engaging mechanism, whereby linear motion of said driving pivot causes motion of such load along such curved path.
- 2. A drive system, according to claim 1, wherein said base further includes a substantially straight track, said substantially straight track being substantially parallel to said drive screw, said linearly driven member further including a straight track engaging roller engaging said substantially straight track to react forces transverse to said drive screw whereby bending moments on said drive screw are reduced.
- 3. A drive system, according to claim 2, wherein said substantially straight track is substantially coplanar with said curved track.
- 4. A drive system, according to claim 3, wherein said substantially straight track is a substantially straight slot in a substantially planar portion of said base.
- 5. A drive system for a plug door of a vehicle having a sidewall, said drive system for moving said plug door along a curved path between a closed position substantially within said sidewall of said vehicle and an open position adjacent said sidewall of said vehicle, said drive system comprising:a base for attachment to said vehicle; a carriage mounted on said base for movement in a transverse direction relative to said sidewall; at lest one elongated support member mounted on said carriage, said elongated support member being substantially parallel to said sidewall; at least one hanger for supporting said plug door, said hanger mounted on said elongated support member for movement thereon; a curved track one of mounted on said base and formed as a portion of said base; a curved track engaging roller mounted on said hanger, said curved track engaging roller engaging said curved track; a linear drive mechanism including a linearly driven member, a driving pivot, a pneumatic cylinder, a drive nut having a linear power connection to said cylinder, said drive nut engaging a drive screw to be driven thereby, whereby said linear motion of said drive nut imparts rotation motion on said drive screw and hence said driving pivot; and a drive link attached to said driving pivot at a drive force receiving end of said drive link, said drive link having a driven pivot at a drive force communicating end of said drive link, said driven pivot being attached to said hanger, whereby linear motion of said driving pivot causes motion of said door along said curved path, whereby plug door moves between said closed position substantially within said sidewall of said vehicle and said open position adjacent said sidewall of said vehicle.
- 6. A drive system, according to claim 5, further including a substantially straight track, said substantially straight track being substantially parallel to said drive screw, said linearly driven member further including a straight track engaging roller engaging said substantially straight track to react forces transverse to said drive screw whereby bending moments on said drive screw are reduced.
- 7. A drive system, according to claim 6, wherein said substantially straight track is substantially coplanar with said curved track.
- 8. A drive system, according to claim 7, wherein said substantially straight track is a substantially straight slot in a substantially planar portion of said base of said drive system and said curved track is a curved slot in said substantially planar portion of said base.
- 9. A drive system, according to claim 6, wherein said substantially straight track is sufficiently long that said link acts as an overcenter lock to lock said door in said closed position.
- 10. A drive system, according to claim 5, wherein said driven pivot is attached to said hanger by a drive bracket, said drive bracket providing an offset of said driven pivot from said hanger in an inward direction relative to said sidewall of said vehicle.
- 11. A drive system, according to claim 5, wherein said curved track is so configured that said link provides a high mechanical advantage for forcing said door to said closed position.
- 12. A drive system, according to claim 5, wherein said base includes, at each end thereof, a channel member oriented in said transverse direction and said carriage includes rollers engaging said channel member to permit said movement in said transverse direction.
- 13. A drive system, according to claim 5, wherein said rotary power connection includes a pair of meshing gears.
- 14. A drive system for a pair of biparting plug doors consisting of a first door and a second door, said biparting plug doors for a vehicle having a sidewall, said drive system moving said first door along a first curved path between a first door closed position substantially within said sidewall of said vehicle and a first door open position adjacent said sidewall of said vehicle, said drive system simultaneously moving said second door between a second door closed position substantially within said sidewall of said vehicle and a second door open position adjacent said sidewall of said vehicle, said drive system comprising:a base for attachment to said vehicle; a carriage mounted on said base for movement in a transverse direction relative to said sidewall; a first elongated support member mounted on said carriage, said first elongated support member being substantially parallel to said sidewall; a second elongated support member mounted on said carriage, said second elongated support member being substantially parallel to said sidewall; a first hanger for supporting said first door, said first hanger mounted on said first elongated support member for movement thereon; a second hanger for supporting said second door, said second hanger mounted on said second elongated support member for movement thereon; a curved track one of mounted on said base and formed as a portion of said base; a first curved track engaging roller mounted on said first hanger, said first curved track engaging roller engaging said curved track; a first linear drive mechanism including a first linearly driven member, a first driving pivot, a pneumatic cylinder, a first drive nut having linear power connection to said cylinder, said drive nut engaging a first drive screw to be driven thereby, whereby said linear motion of said drive nut imparts rotation motion on said drive screw and hence said driving pivot; a first drive link attached to said first driving pivot at a drive force receiving end of said first drive link, said first drive link having a first driven pivot at a drive force communicating end of said first drive link, said first driven pivot being attached to said first hanger, whereby linear motion of said first driving pivot causes motion of said first door along said first curved path, whereby said first door moves between said first door closed position substantially within said sidewall of said vehicle and said first door open position adjacent said sidewall of said vehicle; a second linear drive mechanism including a second linearly driven member, said second linearly driven member including a second driving pivot; and a second drive link attached to said second driving pivot at a drive force receiving end of said second drive link, said second drive link having a second driven pivot at a drive force communicating end of said second drive link, said second driven pivot being attached to said second hanger, whereby linear motion of said second driving pivot causes motion of said second door along said second curved path, whereby said second door moves between said second door closed position substantially within said sidewall of said vehicle and said second door open position adjacent said sidewall of said vehicle.
- 15. A drive system, according to claim 14, wherein said linear drive mechanism further includes:a second drive screw connected to receive rotary power from said first drive screw; and said second linearly driven member including a second drive nut engaging said second drive screw to be driven thereby, whereby rotation of said second drive screw causes said linear motion of said second drive nut and hence said second driving pivot.
- 16. A drive system, according to claim 15, wherein said base has a substantially planar portion disposed beneath said first drive screw, said first drive nut and said first drive link, said substantially planar portion further being disposed above said second drive screw, said second drive nut and said second drive link, said curved track being formed as a curved slot in said substantially planar portion of said base.
- 17. A drive system, according to claim 16, further including:a straight track formed as a straight slot in said substantially planar portion of said base, said first linearly driven member including a first straight track engaging roller engaging said straight track to react forces transverse to said first drive screw whereby bending moments in said first drive screw are reduced; and said second linearly driven member including a second straight track engaging roller engaging said straight track to react forces transverse to said second drive screw whereby bending moments in said second drive screw are reduced.
- 18. A drive system, according to claim 17, wherein said straight track is sufficiently long that said first drive link and said second drive link act as overcenter locks to lock said first door and said second door in said closed positions.
CROSS-REFERENCE TO RELATED APPLICATIONS
The present invention is closely related to patent application titled: Plug Door Drive System, which was filed in the U.S. Patent and Trademark Office on Oct. 13, 2000 and bears Ser. No. 09/687,339, now Pat. No. 6,539,669. The referenced patent application has two inventors in common with the present application and is incorporated herein by reference thereto.
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