. Canadian engineer. f the six i66 THE CANADIAN ENGINEER ohimc ^o. carrying cables is 20,000 lbs. The earth pressure is68,300 lbs. The moment of ihe overturning forces aboutthe toe of the anchorage is, therefore, 28, ft.+120,000 :< fl. + 68,300 X 20 ft., equals 4,744,000 The weight of the concrete is 1,481,800 lbs., andthe resisting moment is 1,481,800 x ft., equals25,042,420 ft. lbs. There is, therefore, a factor of safelyof over 5 in respect to the overturning of this is a factor of safety of about 8 at ThompsonsPoint. For any position of the car,
. Canadian engineer. f the six i66 THE CANADIAN ENGINEER ohimc ^o. carrying cables is 20,000 lbs. The earth pressure is68,300 lbs. The moment of ihe overturning forces aboutthe toe of the anchorage is, therefore, 28, ft.+120,000 :< fl. + 68,300 X 20 ft., equals 4,744,000 The weight of the concrete is 1,481,800 lbs., andthe resisting moment is 1,481,800 x ft., equals25,042,420 ft. lbs. There is, therefore, a factor of safelyof over 5 in respect to the overturning of this is a factor of safety of about 8 at ThompsonsPoint. For any position of the car, the tension in the lowertraction cable between the car and the transmissionsheave equals half the counterweight, or 10,000 lbs.,neglecting friction of counterweight and sheaves. Thetension in the reinaining part of the traction cabledepends on the position of the car, varying from 6,000lbs. when the car is at Thompsons Point to 14,000 the car is at Colts Point. The traction cable has ^SlO-*»rtl JO<t.«*. - t,,i 6v! Fig. 12.—Detail of 10=ton Weight Box for Track Cable. a strength of 70,000 lbs., so this allows a factor of safetyof more than 4, after deducting from strength of cablefor bending over sheaves. The sag of the track cables unloaded is ft. Themaximum sag when loaded with car and passengers ft. The car will still be 148 ft. above the surfaceof the water at the point of maximum sag. The maximum vertical travel of the track weightboxes, allowing for change in length of cables due to125° variation in teinperature, and due to difference indeflections, is 11 ft. 2 in. The possible vertical travel isabout 19 ft., thus providing for oscillations due to breaksof cable. The maximum vertical travel of the traction cablecounterweight is 8 ft. 8 in. The possible travel is 15 ft. The grade of the track cables varies from 16 percent, at either landing to per cent, at the centre ofspan. The maximum grade, therefore, is 16 per cent.,and the average
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