This section is from the "Modern Machine Shop Construction, Equipment, And Management" book, by Oscar E. Perrigo. Also see Amazon: Modern Machine Shop Construction, Equipment, And Management.
The Franklin portable crane is simply a small jib crane on wheels, which may be moved about the shop as easily as a hand truck. Its capacity is from one and a half to three tons. It readily lifts and holds the load at any point so that it can be wheeled to any desired location. It is now made also with a gasoline motor, or an electric motor run by a storage battery for both propulsion by traction wheels and the power for lifting - making a very complete and portable power crane for many ordinary shop purposes. It will be found a very convenient and useful addition to the shop equipment.
The traveling cranes provided for in the various departments do not seem to need any detailed description. There are many excellent ones in the market and they should be selected with a view to the special requirements of each case.
In considering a system of tracks for yards, and the system for the construction of cars for use upon these tracks, the Hunt system is probably the best and most complete of anything in the market, particularly when heavy work is to be undertaken. However, for moderate loads a more economical method of construction may be adopted, and one that may be built in the shops without a great outlay for patterns or special tools.
Metallic ties are no doubt the ideal method for laying track on the ground when steel rolled track is used. Yet a cast iron track, properly constructed and properly supported, will be found very practical for every-day service in a plant of such a character as the one under consideration. Again, where track is to be laid on upper floors it would not seem advisable to use the heavy plate track made of cast iron on account of its considerable weight. Much of this is not necessary for the purpose, particularly when moderate loads are to be transported, as is usual with work done on the floors above the first; and all excess of weight is not only detrimental, as unnecessarily loading down the building, but adds needlessly to the expense. In fact the principal requirements of a floor track would seem to be these: First, it should be on a level with the top of the floor, so as not to offer any obstruction to the workmen going from place to place, or to the passage of hand trucks over it. Second, it should be of such moderate weight that it may be laid down on any floor of the building without overweighting it. Third, it should be of such simple construction that an ordinary mechanic may build one, put it in operation and repair it. Fourth, it should be so designed that cars having a fixed wheel base may readily run around its curves without undue friction. Fifth, it should be of such depth that it may be easily laid down by cutting through the usual two-inch plank floor of the ordinary machine shop, or laying the track first in the case of a new shop being erected, and fitting the floor around it.
A track designed and constructed in conformity with these conditions is illustrated in the drawings accompanying this chapter. Fig. 132 is a plan of a section of straight track joined and secured to a 90-degree curve. Fig. 133 is a section of straight track in connection with a left-hand switch. Fig. 134 is a cross-section of the straight track, on an enlarged scale. Fig. 135 is a cross-section of curved track, also on an enlarged scale. All of these views show the track and its supporting timbers as arranged and laid in the shop yards. Fig. 136 is a cross-section on a still larger scale, showing the relation of the straight track and a portion of the rim of a car wheel. Fig. 137 is a similar section showing the position of the wheel on the outer rail of a curve.
Upon a straight track it is a simple matter to construct wheels or track that will run properly and work freely without undue friction or grinding upon the edges of the rails.
When the curves are considered quite a different problem presents itself. The outer rail upon a curve being considerably longer than the inner rail, means must be provided for compensating for this difference so that there may be no slipping of either wheel of the car when passing around the curve, in the case of the usual four-wheeled cars whose wheel axles are journaled in fixed boxes. To provide for this condition the groove in the track is considerably widened, whereby the wheel flange may have ample space to run from side to side. The wheel is constructed with an inclined face, representing a short section of a cone. It is considerably wider than the portion of the track upon which it runs, as will be seen by referring to Figs. 136 and 137. The action of this arrangement is as follows: When running on a straight track the position of the wheels on the track will naturally be midway, in consequence of the reversed position of the inclined tread of the wheels. When the car arrives at a curve the natural tendency is toward the outer rail. This tendency will throw the outer wheel up on its largest diameter and at the same time bring the bearing of the wheel on the inside of the curve to its smallest diameter. This variation of diameters will be sufficient to compensate for the increased length of the rail on the outer side of the curve and the car will run smoothly around it. The difference between the width of the groove in the straight track and that on the curves is arranged for by narrowing the groove in the curved track to the proper width in the final 8 or 10 inches from the end where it joins the straight track. The dimensions of the track are given in Figs. 136 and 137.