Sec. 957. [=Duties of machine men.=] Machine runners and helpers shall use care while operating mining machines. They shall not operate a machine unless the shields are in place, and shall warn persons not engaged in the operating of a machine of the danger in going near the machine while it is in operation, and shall not permit such persons to remain near the machine while it is in operation. They shall examine the roof of the working place and see that it is safe before starting to operate the machine. They shall not move the machine while the cutter chain is in motion. When connecting the power cable to the electric wires, they shall make the negative or grounded connections before connecting to the positive, and when disconnecting the power cable, shall disconnect from the positive line before disconnecting the negative or grounded. When positive feed wires extend into rooms, they shall connect such wires to the positive wire on the entry before connecting the power cable, and as soon as the power cable is disconnected shall disconnect such wire from the wire on the entry. They shall use care that the cable does not make contact with metallic rails of the track, and shall avoid, where possible, leaving the cable in water. If they remove props which have been placed by the miner for the security of the roof, they shall reset such props as promptly as possible. (Sec. 941; Penalty, Sec. 976.) Sec. 958. [=Duties of motormen and trip-riders.=] Motormen and trip-riders shall use care in handling the locomotive and cars, and shall see that the signal or marker, as provided for, is used as provided, and shall be governed by the speed provided for in this act in handling cars. They shall not run the locomotive with the trolley ahead of the locomotive, except in cases where they cannot do otherwise, and then only at a speed of two miles per hour. They shall warn persons forbidden to ride on the locomotive or cars, and shall not permit such persons to ride on locomotive or cars contrary to the provisions of this act. [=Duties of trip-rider, rope haulage.=] The trip-rider in charge of rope haulage trips shall see that the signal light, as provided for in this act, is in place and in proper condition before starting trip. [=Drivers.=] Drivers shall use care in handling cars, especially going down extreme grades, and at junction points. [=Those in charge of trips of cars shall see that doors are closed.=] Motormen, trip-riders and drivers in charge of haulage trips passing through doors used as a means of directing the ventilation, shall see that such doors are closed promptly after the trip passes through. (Sec. 923, 943, 961; Penalty, Sec. 976.)