The haulage system employed to convey coal from the face to the outside, dates back to 300 B. C., when slaves carried the mineral from the face to the consumer. The British discovered coal on their island about 800 A. D. and they were the first people to make practical use of coal and make coal mining a successful operation. The Britons carried cargoes of coal in their trading expeditions long before Columbus discovered America. The early history of mine haulage in the British mines relates to women with baskets, a practice still in use in Korean mines.
Coal was discovered in America in 1679. The first mine worked in the United States was opened at Richmond, Va., in 1770. The haulage inside consisted of a crude sled loaded with sacked coal ready for the market and drawn by a mule. The tipple consisted of the very simple operation of loading the sacked coal to the back of a lame mule, which represented the transportation system between mine and boat. The capacity of the boat was one ton and this large production of coal was intrusted to a small boy, who delivered to any place in town his bushel basket filled with winter fuel. One daring coal operator shipped fifteen tons of coal by boat to Philadelphia and the man in charge had to seek employment to pay his board while finding customers for his fuel.
A production of five tons per day would hardly attract attention to any system of haulage, add three ciphers and the importance of mine haulage is made very plain to the management. I will consider a production between 3000 and 5000 tons in eight hours and endeavor to bring out the essential features necessary to make the haulage system a regulated precise factor.
There are two phases to mine haulage, the mule trip from the room to the motor or gathering party and the main haul to the outside. The motive power, whether done by mule, wire-rope or electric motor cannot be effective if left to the power alone. Conditions must offer no obstacle and it is the removal of obstacles that make the haulage system. This paper will consider a flat seam with the usual jump ups and downs or natural obstacles to be met and mastered by the successful tail-rope or electric system.
The pit car is no longer a screening system scattering the fine coal from the room to the outside, adding to the costs by giving employment to road cleaners and polluting the ventilating system with a fog of coal dust. It is not a contrivance with four flat wheels and a labor killer in the room or on the tipple. The large producing mine has a pit car with a tight body, roller-bearing wheels, with a self-oiling system that offers the least possible draw-bar pull to overcome the friction resistance, a hand brake conveniently placed and positive in action, a wheel base short enough to make room necks and long enough to hold the car in traveling balance, hitchings that are simple, free to move, hold fast and easily disconnected. The capacity of a pit car is regulated by the height of the coal or over-head clearance, but the maximum limit is about two tons.
Cross-entries should be turned off from the main entry with the future view of a motor road, and motor lines should keep as close to the working face as the grade will permit. Make the mule hauls as short as possible and reduce the number of pit cars by a rapid transit system. Room tracks should be free from gob and offer no obstacles to the driver or mule. Cross-entries should be properly timbered, free from gob, sprinkled and equipped with adequate gathering-parting space.
All, electric lines should be placed with the intake air, trolley lines protected with guards at partings, pass-bys and every place where a man has to work and the line made dead-end to the approach of a mule terminal with an entry fence to keep animals from the live wire. Accidents are a source of delay to mine haulage and safety first is the factor that permits of rapid transit.
Main line haulage should be by three-entry system, two intakes, one used for the loads and the other for the empties. A telephone system should follow both roads with the telephones placed at reasonable intervals. A fall on the loaded or empty track could be overcome by using a single track and dispatching the motor trips by telephone. Every switch off the main road should be protected with danger or red lights up the entry for a distance, suitable as a warning to an approaching trip.
All partings on a grade should be provided with safety blocks and loaded trips on a grade should have a drag.
The least number of doors on the haulage road gives the trip free action, without any change in the circulating system and, briefly a good haulage system depends to some extent upon permanent splits by means of over-casts.
Motor roads should be graded, equipped with heavy steel, every curve flattened to the maximum limit and every switch a positive throw type. Railroad ties and 60 pound steel have saved lost time, due to the track spreading, saved money for road cleaning, due to coal being bounced off over a rough track, and permitted faster movement of the trip with safety.
I have not touched on the various systems for motive power, other than that of the electric motor such as engine-planes, endless rope, gravity-planes and tail-rope. The pitch of the coal seam brings one system or another into play and each system will have a definite merit. The endless rope has not proven a success under ground, but it has been employed for surface use with satisfactory results. Gravity planes have caused more deaths and injuries under-ground than any other haulage system and very few mines employ this system under-ground; however, it has proven of service for outside use. The tail rope system is being rapidly replaced by the electric motor, but it has an advantage up to a limited capacity in mines with an uneven grade. The engine-plane or electric hoist, is the only means for pitching veins and the production does not as a rule exceed 2000 tons per main haulage entry.
Main line haulage has received a great deal of attention and it is remarkable the large tonnage handled by means of telephone despatching when the outside and inside are pulling together, but the single track system is easily upset by the delay of a single motor and it is this occasional delay that calls for a two-track system to insure a more perfect haulage system.
The first phase of mine haulage, that of gathering, has the obstacles to contend with that nature has placed and problems that must be overcome with the least expenditure of money. Brushing to give head room for the mule is expensive for the initial operation and very often causes a roof condition that means a large amount of money for timber. A serious grade means more mule power, more delay in placing and removing cars and a handicap to the miner at the face. Obstacles that are taken as a matter of fact and usually met by a hammer and tongs system are to be mastered by aid of the electric mule.
The electric mule is a small storage battery motor of two types. The first depends upon storage batteries alone and a recharge during a possible 12 hours of idleness and can be compared with the electric lamp used by the miners. The second type is a trolley-driven motor along the entry and a storage battery motor up the room. This type of motor is charging and discharging automatically. The two types serve their purpose in taking the place of a mule in a low place without excessive brushing, a maximum amount of speed and power enough to make grades without the assistance of another electric mule, as would be the case with animals.
Primero mine has an electric mule of the storage battery type and it is proving an essential item in mine haulage. The cost of operation must not be considered at this time with a very small expense for repairs and upkeep. As a mine haulage unit, this motor is taking the place of six mules, two drivers and increasing the production from 40 tons , to 80 tons. The results show that the haulage system, has been improved by the introduction of the storage battery motor and the cost of upkeep, even if the cost should prove to be high, will be very much lower than the necessary brushing for mules without taking into consideration the cost of stable expense as an item to be compared with motor upkeep.
In conclusion, I will state that mine haulage depends upon good ventilation, heavy steel, graded tracks, elimination of short curves, a system for despatching trips, safety precaution and a rapid movement from the face to the outside.