Show the r I 1 y he ar jeffrey mining ing M machines achiles WRITTEN F FOR OR THE MINING REVIEW I 1 the jeffrey mining machines with flame ti tight t ht motors and starters shown in the accompanying compa nying illustration were brought out almost simultaneously with the publication of the british departmental committees report upon the use of electricity in mines this rep report ort which embodies rules for the use of electricity in mines recommends the adoption of entirely enclosed motors and auxiliary devices such as starters terminals etc for all mines coming under general ture is drum wound with machine formed coils the pole pieces are of laminated sheet steel and the windings of both the armature and field coils are insulated in the most approved manner for mining machino machine service this service by the th e way is probably the most severe of any service which electric motors are called upon to perform the insulation has to withstand both oil and moisture as well as heat and infinitely more dirt and less attention figure no I 1 rule no 8 of the coal minos mines regulation act of 1887 mining machine motors of necessity have to be designed to be very compact it is therefore necessary that every advantage be taken of space so that the motors will not heat excessively under their regular duty in this country where our mines are very free from gas the open type of motor has found favor on account of its accessibility and on account of the fact that the same than in any other service known the motors illustrated are provided with self oiling ring oiling bearings which are so arranged that the oil hermetically seals the motor so that any gas which may accumulate about cannot possibly be ignited by sparking at the brushes or any interior trouble with the motor over the of this motor is a plate glass door protected by a heavy malleable iron lid through the plate glass door the brushes may be observed without MR woo kw figure no z motor capacity can be put into smaller space in the open type than in the enclosed type by careful designing however the jeffrey manufacturing company have been able to put upon their mining machines motors of the enclosed type which are of equal capacity to those of the open type formerly used and the enclosed motors occupy practically no more space than those of the open type the jeffrey 21 A mining machine motor which is typical of other enclosed mining machine motors made by this company is a modern motor in every respect the arma opening the motor to mine gasses the starting switch for this motor is protected in a similar manner to the motor itself all contacts bein being hermetically sealed i in flame tight metal casings the inspector for the british government who recently inspected these motors pro bounced them as conforming in every particular to the rules and requirements of the departmental committee i an advantage of these motors is that they can be applied directly to jeff jeffrey rey mining machines with no other change than the thea removal of the existing open type motors they are wound for standard voltages of and volts and may be wound special for other voltages where requirements ments demand it attempts have been made by manufacturers of coal cutting machines other than yie the jeffrey manufacturing company to develop an enclosed type motor which motor would not only conform to the rules and requirements quire ments of the english government but would at the same time be an efficient motor and one so designed as to reduce to the lowest possible point the expense of keep I 1 up but up to this time no such motors has been put upon the market by any builder save the jeffrey manufacturing company this company has not only brought out the r 21 A motor for what is commonly design designated abed as the standard type of chain breast ma Z chine but they have also brought out the 1 1 27 A motor which is a motor of the enclosed type conforming strictly to the mining in laws which is adaptable to low or thin vein machines the demand tor for such machines equipped with both of these motors has been very extensive and since the mo tars were put on the market machines equipped with same ame have been ordered by the largest coal companies not only in great britain but in the english colonies where the rules of the home government are effective fec tive fi fiure figure ure I 1 shows the 21 A coal cutter equipped with enclosed type motor and figure 2 shows the 27 A coal cutter which is a low vein machine equipped with enclosed motor |