STAIR CLIMBING TRACKED VEHICLE

摘要

1491555 Wheel chairs for ascending stairs RAMBY Inc 21 Jan 1975 2643/75 Headings B7D B7E and B7H A tracked wheel chair capable of negotiating stairs comprises a pair of auxiliary tracks 32 pivoted to main tracks 22, a self levelling seat 54 and a linkage 70 for controlling pivotal movement of the auxiliary tracks. For normal travel the auxiliary tracks are pivoted upwardly about shafts 36, which also mount the main track drive sprockets 26, and wheels 62 at the rear of the auxiliary tracks contact the ground lifting the front ends of the main tracks. Drive to sprockets 26 may be via hand cranks 40, 401 and chains 44, 441 or by an electric motor and each main track may be driven independently. Linkage 70 includes a piston/cylinder device 84, 86 and an arm 73 connected by a joint which may be locked to hold the auxiliary tracks pivoted upwardly (Fig. 14a, not shown). Release of the joint (Fig. 14b, not shown) also releases a catch 80 holding the piston/cylinder device, and the tracks lower under gravity without extending the device until they pass below the horizontal. The device 84, 86 includes a restriction to prevent rapid movement of the auxiliary tracks. Seat 54 is supported on a pedestal 52 pivoted about shafts 36 and is moved in response to an inclination sensor to keep the seat level via a motor 90 and screw jack 92. The sensor includes a damped pendulum element (Fig. 15, not shown). Fail safe devices are provided to ensure that the wheel chair cannot descend stairs unless positively driven and cannot slide back whilst ascending.