It is often necessary, at least during the early stages of building construction, to locate the hoisting engines in the public highway. This must necessarily result in obstructing traffic to some extent, and there are also various other objections to this arrangement, so that it is desirable to install the engines within the building as soon as the work has advanced to a stage where it is possible to do so. There are many advantages to be gained by placing the engines on the second-floor level, particularly on large construction jobs, because here they are out of the way of trucks or wagons that are often used for bringing supplies and materials into the building. (See paragraph 69 for suggestions concerning the storage of materials in buildings under construction.) Furthermore, this arrangement simplifies the protection of the hoisting cables and signal cords or wires.

Regardless of the location of the hoisting engines, substantial roofs should be erected over them to intercept falling objects; and it is preferable to entirely inclose them, to protect the operators and the engines from inclement weather, until such time as the permanent floor immediately above is in place, and the walls of the building have been carried up beyond the floor level on which the engines are situated. Whenever the hoisting engines are placed in the street, all large structural steel members and blocks of stone, and all other heavy and massive objects should be hoisted on the side of the building opposite to that on which the engines are installed, when conditions will permit. Serious accidents have occurred when this precaution has been neglected.

* Derricks are separately considered in Section V.

Fig. 19. Hoisting under Dangerous Conditions.

24. Types Of Hoisting Engines

Hand-operated derricks and hoists of various types are quite generally employed on small construction jobs, and for certain parts of the work on larger ones. In large operations, however, steam engines or electric motors are indispensable. Provide effective protection for the exposed gears of all hoisting engines and motors, and guard all crank-shafts, sprocket wheels and chains, projecting set-screws and keys, and all other dangerous moving parts. See that a suitable space in the vicinity of hoisting engines is kept clear of unnecessary ropes and other objects that might become caught in the moving parts. If the hoisting engine or motor is installed on a platform or in any elevated position where the space is limited, provide railings and toe-boards at all points where protection of this kind is needed. Provide adequate and effective brakes for every hoisting engine, capable of holding the maximum load in any position. All hoists should be kept under perfect control at all times, and particularly when lowering heavy loads.

25. Boilers

Give special attention to the boilers of all steam hoisting-engines, because the conditions under which they are operated are likely to cause more rapid deterioration than would be the case with stationary boilers. Periodical inspections by experts are essential, and all recommendations made by them should be promptly and carefully attended to. See that each boiler is provided with a reliable safety-valve, steam gage, water column, gage glass, and try-cocks, and test all of these devices frequently to make sure that they are in good working order. An approved gage-glass guard is highly important for each steam boiler, because the conditions under which the boiler is operated are such that the gage glass may easily be broken. Keep the interior surfaces of the boiler clean, and free from scale and sediment. Provide a suitable strainer or filtering device of some kind if the feed water is likely to contain suspended impurities in sufficient quantity to settle inside the boiler and cause damage. Do not leave the fire door open to check the fire, and so far as possible avoid opening it at frequent intervals for other purposes. Cold air, entering the fire door and coming in contact with the highly-heated portions of the boiler, is likely to cause severe strains which may ultimately result in serious damage. Before leaving for the night make sure that there is plenty of water in the boiler, and that the fire is properly banked and checked; and always ascertain the level of the water before unbanking the fire in the morning. See that all steam and water connections about the boiler and engine are kept tight, to prevent scalds and burns.

Fig. 20. Unprotected Hoisting Motor, Cables, and Guide Blocks.