Gravity roller conveyors

An elevator for raising a load from an infeed position to a discharge position which elevator comprises

• a. a platform for supporting the load, the platform having an upper part on which rollers are mounted in the infeed direction, and a lower part on which wheels are mounted at right angles to the rollers, the upper and lower parts being secured together by springs such that when the springs are uncompressed the rollers provide a first low friction surface and when the springs are compressed the wheels project through the spaced between the rollers and provide a second low friction surface at right angles to the first low friction surface, the platform being adapted in use to be inclined to the horizontal about a first axis at the infeed position and inclined to the horizontal about a second axis at the discharge position, the first and second axes not being parallel,
• b. means for changing the inclination of said platform during its elevation from the infeed position to the discharge position,
• c. a pneumatic ram for elevating said platform and said load from the infeed position to the discharge position and for lowering said platform from the discharge position to the infeed position, the pneumatic ram being attached to the underside of the lower part of the platform by the cooperation of a ball carried on said ram and a ball socket on the underside of the lower part of said platform,
• d. means preventing infeed of a load other than when the platform is in the infeed position, and
• e. means preventing discharge of a load other than when the platform is in the discharge position.