Fig. 4 (missing) represents a brace bar, serving to attach the drilling apparatus and support it in place of the tripod Fig. 1, or the platform and stand Figs. 2 and 3. It is very suitable for drift work and those situations where the lighter brace will answer as well as a tripod.
Fig. 5 shows the tunnelling machine. This consists of a light car, provided with a vertical arm on which a brace can be run up against the roof to hold the car firmly in position. At the base of this arm a strong horizontal beam projects beyond the front of the car, this beam resting on a pivoted joint and being moved up and down by a screw. It works between curved guides, which give it steadiness, and at the forward end is another vertical screw, which is also run up against the roof. It is plain that all these braces are ample to give the beam the required rigidity. The whole is mounted on an iron plate which has a certain amount of side motion on the car, so that any desired direction, not parallel to the line of rails on the tunnel floor, can be given to the whole system. On the end of this beam, and at right angles to it, is a horizontal bar which carries the drills. The bar can be moved in and out, so that when projections of rock prevent the approach of the car itself to any given part of the face, the long projecting arm and the mobility of the drill-carrier allow the approach of the drills themselves close to the face. This obviates the necessity of using long drills, which strain the machinery. Each drill, as mounted on the bar or carrier, in addition to the motions described above, which it receives in common with the whole system, is capable of complete horizontal and vertical revolution.
It will be seen that when the whole machine has received the necessary general direction, each one of the drills can be made to play upon any point, above, below, behind, or in front of the carrier to which it is attached. The "tunnel drill" is therefore a complete tunnelling machine, capable of excavating over a very large mining face. From 4 to 8 drills may be mounted upon this car.
In regard to sizes of these machines, the smallest is a 2.5 inch (the piston diameter) drill, used for quarry work, gadding, etc. It is light, weighing only 123 pounds, bores any hole from 1 to 1.75 inches, has a stroke of 3.5 inches, and delivers 800 blows per minute. At the celebrated Palmer mine of magnetic iron ore, owned by Messrs. J. & J. Rogers, Ausable Forks, N. Y., one of these bored 170 feet of 1.25 inch hole in ten hours. The next larger size has a 3.25 inch cylinder, makes 5 to 7 inch stroke, gives 500 blows per minute, and weighs 295 pounds. It will bore a 1.5 to 2 inch hole to the depth of ten feet. The 4 inch drill has a 7-inch stroke, gives 400 to 500 blows per minute, and weighs 472 pounds. It bores to 3 inches diameter and to 15 feet in depth. The largest size has a piston of 5 inches diameter. In soft rock an 8-inch stroke, with 400 blows per minute, is used. In hard rock the stroke is only 5 inches. It will work to a depth of 40 feet, and bore a hole from 2 to 5 inches in diameter; its weight is 558 pounds, but it is made in sections so that no piece weighs more than 150 lbs. These machines can be worked by compressed air or steam, as desired. In fact these drills have a history behind them that is a sufficient guarantee of their quality. They are all built to a fixed scale, so that repairs or renewals are easy and cheap.
For these reasons it is not surprising that we see them so largely introduced, for instance, drills at Bergen Avenue, New York, in the hardest rock found on this part of the American continent, known as crystalline trap; for the Easton & Amboy Railroad tunnel, near Bethlehem, N. J., twenty-one of three these drills have been purchased. At Pilot Knob and Iron mountain, Mo., they are testified to do more work, and at a greatly reduced cost, than any other drill.
We close with a copy of the report upon rock drills by the judges of the American Institute, at its forty-second exhibition, awarding the silver medal. They say: "The Ingersoll rock drill is superior to all others on exhibition, for the following several reasons, to wit:
- Its greater effective drilling power.
- Its simple construction, there being but few working parts.
- Its portability, both as to weight and adjustability of the tripod supporting drill, allowing its use in very narrow cuts, especially in excavating for sewers, and for which purpose it appears to be superseding all other machines.
- The elastic cushions at each end of the cylinder protects the cylinder heads from injury when the piston is suddenly relieved from pressure, as when the drill passes through wide seams in rock.
- Its having an automatic feed, thus giving it a steady motion in proportion to the power used.
- Its greater steadiness when at work, there being an absence of much of the jar and vibration experienced in most other drills, which must be very destructive to their working parts.
- Its greater power in proportion to size and weight, the force and rapidity of the blow being in proportion to the surface of piston, is some forty per cent in favor of the Ingersoll drill.
- The facility with which all the parts can be renewed when necessary, all being made to conform to exact models. In conclusion, we would recommend for the Ingersoll rock drill, the Great Medal of the American Institute, for the reason that we adjudge it so important in its use, and so complete in its construction, as to supplant every article previously used for accomplishing the same purpose."
In conclusion, we would recommend for the Ingersoll rock drill, the Great Medal of the American Institute, for the reason that we adjudge it so important in its use, and so complete in its construction, as to supplant every article previously used for accomplishing the same purpose.
Page 2 of 3