Patent ID: 7225743
Filing Date: 2007-06-05
Classification: B61B

Abstract:
1. A propulsion unit for moving a vehicle along an elongated power tube having an interior adapted to be selectively pressurized and an exterior along which a vehicle travels, the propulsion unit comprising first and second, diametrically opposed interior rails attached to an interior of the power tube, and a thrust carriage comprising a main body arranged between the first and second rails, first and second wheels rotatably mounted to a first side of the body proximate the first rail, at least a third wheel rotatably mounted to the body on a second side of the body proximate the second rail, a device for resiliently biasing the third wheel towards the second rail, the wheels having a grooved periphery shaped so that the first rail extends into the grooved periphery of the first and second wheels and the second rail extends into the grooved periphery of the third wheel as a result of a biasing force generated by the device, and a coupler for coupling the thrust assembly to the vehicle, a support frame supporting the power tube on the ground and including spaced-apart uprights disposed proximate an exterior of the power tube, and fasteners securing the first and second rails to the uprights of the support so that the weight of the propulsion unit is carried by the uprights without subjecting the power tube to stress.