Stacker hopper with feed interrupt

A method of operating a sheet stacking system, the sheet stacking system comprising:

• a conveyor configured to carry sheets from a conveyor intake end to a conveyor discharge end;
• a hopper at the discharge end configured to receive the sheets ejected from the discharge end of the conveyor and guide the sheets as they fall in a cascade path onto a platform associated with the hopper, the falling sheets forming a main stack on the platform, the hopper including a backstop facing the discharge end of the conveyor such that the sheets ejected from the discharge end impact against the backstop before forming the main stack,
• a first accumulator mounted on and supported by the hopper, the first accumulator comprising a carrier and at least one first support extending from the carrier through the backstop, the at least one first support being shiftable from a retracted position to an extended position relative to the backstop, the carrier being movable linearly and vertically relative to the backstop with the at least one first support in the extended position between a raised location with the at least one first support outside the cascade path and a lowered location with the at least one first support in the cascade path, and
• at least one second support below the conveyor discharge end configured to shift between a retracted position outside the cascade path and an extended position in the cascade path, the at least one second support being located substantially horizontally across the hopper from the at least one first support when the at least one first support is in the lowered location,
• the method comprising:
• placing the at least one support in the extended position and the carrier at the raised location;
• discharging sheets from the conveyor such that they impact the backstop below the at least one support, while the at least one support is in the extended position, and fall onto the platform or onto sheets supported by the platform to form the main stack,
• moving the carrier, with the at least one first support in the extended position, from the raised location to the lowered location while the sheets fall along the cascade path,
• shifting the at least one second support from the retracted position to the extended position, and
• forming a first partial stack on the at least one first support and on the at least one second support above the main stack.