Workpiece singulator with adjustable stair depth

A method of singulating workpieces of various sizes on a set of movable stairs, wherein the set of

• movable stairs includes a first step member and a second step member that are movable along generally parallel paths between a first level and a second level, a third step member and a fourth step member that are movable along generally parallel paths between the second level and a third level, a first drive operatively coupled with the first and third step members, and a second drive operatively coupled with the second and fourth step members, the method comprising:
• operating the first and second drives to move the first and second step members synchronously as a unit to thereby transport a first workpiece from the first level to the second level on the first and second step member;
• and
• operating the first and second drives asynchronously to thereby transport a second workpiece from the first level to the second level on at least the first step member, wherein the second step member is disposed between the first and third step members.

A movable stair system for transporting workpieces, the system comprising:

• a first movable stair having a first step member with a first workpiece support surface and a second step member with a second workpiece support surface, the first and second step members being movable along generally parallel paths between a first level and a second level, wherein the first step member is operable independently of the second step member;
• a second movable stair configured to be movable between the second level and a third level, the second movable stair having a third step member and a fourth step member movable along generally parallel paths between the second level and a third level, wherein the third step member is disposed between the second step member and the fourth step member;
• a drive system coupled with the first movable stair and configured to move the first and third step members independently of the second and fourth step members, wherein the drive system includes a first drive operatively coupled with the first and third step members and a second drive operatively coupled with the second and fourth step members;
• and
• a programmable logic controller (PLC) operatively coupled with the drive system and the sensor, wherein the programmable logic controller is selectively operable to control the drive system in a first mode, in which the first step and second step members are moved asynchronously to thereby singulate workpieces of a first size, and in a second mode, in which the first and second step members are moved in unison to thereby transport workpieces of a larger second size.