Discussion on “the modern electric mine locomotive,” (Bright), San Francisco, Cal., Sept. 17, 1915. (see proceedings for August, 1915)

Wilfred Sykes: The increasing size of mine locomotives and consequently the increased power of the individual units makes it necessary, if a reasonable design is to be made, to find some way of removing the heat from the motor. The use of blowers is a very simple method and is found on all locomotive designs for main line electrification. That increased capacity can be obtained in this way is of course well known, however, this arrangement cannot be used on all types of mine motors. If the motor is not so designed that the air can come in contact with the parts where the heat is generated, the blowing of air through the machine will not very greatly increase the continuous capacity. This has been shown very clearly in attempts that have been made to increase the continuous capacity of large mill motors for ore bridge service. Unless the armature core is provided with ventilating ducts in a similar way to open machines, the forcing of air through the frame makes only a comparatively small difference. In one case which I tested, the continuous capacity was increased only about 15 per cent. This motor had a solid core and forced ventilation had not been anticipated when the machine was designed.