Patent ID: 9731901
Date: 2017-08-15
CPC Classifications: B65G

Claim:
1. A conveyor system, at least one portion of the conveyor system traversing a continuous slope sufficiently steep such that tensile forces associated with overcoming the effects of the continuous slope are several times larger per unit length of run than tensile forces per unit length of run due to main frictional resistance of the conveyor system, the conveyor system comprising: an external belt defining a continuous loop, the continuous loop traversing the entire route of the conveyor system and configured to carry material load to be transported across the entire route; an external drive having a first torque output; at least one internal belt positioned inside the continuous loop of the external belt and traversing at least a portion of the continuous slope, an upper side of the at least one internal belt configured to operably engage an underside of the external belt so as to frictionally drive a portion of the external belt, wherein the stiffness of the inner belt is at least as stiff as the outer belt; and an internal drive having a second torque output, wherein the first torque output is approximately equal to the torque required to move a total mass of the portion of the external belt not resting on the internal belt and the second torque output is approximately equal to the torque required to move a total mass of the portion of the external belt resting on the internal belt, with the conveyor system being configured such that, at the portion of the external belt driven by the at least one internal belt, the external belt is configured such that the rate of tension rise in the external belt is configured to be approximately zero or a modestly higher rate.