Bed Concept Details

  Drawing up a Rube Goldberg contraption of a bed was all fun, but how to make it actually work ? Strong enough rails, sliding up & down, extending in width, 2 unsupported corners... Each a challenge.

  Fortunately, anything is possible on a computer, and it soon looked like this:
 
  From left to right:
  • the extension fingers slide out to increase the width of the bed when down
  • the main platform consists in finger guides sandwidched between a bottom and a top (not shown) plywood sheet
  • 3 linear actuators slide the extension in / out
  • 2 aluminum arms hold the main platform horizontal
  • each arm is bolted on a carriage that slides up & down inside a rail
  • the 2 rails are bolted to the van's wall on the driver side
  Carriage setup:
 
  From left to right:
  • arm holding the bed's main platform
  • 90° offset brace(*) connecting the arm to the carriage
  • the carriage consists in a 1/2" aluminum blade with 4 sealed bearings
  • each pair of bearings is press fitted together on a shared slotted pin
  • slotted rail
  • inside the rail are 2 sprockets: 1 at the top (free wheeling), 1 at the bottom (connected to the long shaft described below)
  • (not shown) a chain, connected to the top of the carriage via an eyebolt, runs up to the upper sprocket, down between the carriage and the back wall of the rail, around the bottom sprocket, back up to the carriage
  • (not shown) a chain tensioner connects the chain to the bottom of the carriage
  A long shaft then connects the bottom sprocket of each rail together, ensuring that the carriages go up and down in sync. Finally, a motor drives the shaft.
 
  Sorry for the lack of illustration for the sprockets, chains, tensioners and shaft. Poor CAD skills and pure laziness 😅  The mud should clear up soon, though, after the next post that describes the actual build.

 Sounds easy enough ? Ok, it's power tools time then ! What could go wrong... 😏
 
(*) the 90° offset brace is only for the arm closest to the driver. So that the bed platform can overhang past the front rail (due to the Ford Transit's wall details). The arm in the back is directly bolted to its carriage.

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