Bulletin No. 104



Webmaster's Note: This instruction bulletin accompanied a 1941 AR (now AR-3) master clock that was sold on ebay.  The winner of the auction was gracious enough to provide me with a photocopy of his original instruction manual.


(1) The following instructions are general and apply to all standard automatic resetting impulse type clock systems. It is suggested that the entire instruction sheet be read over carefully before attempting to set up, regulate, or put this system in operation. The Home Office or any Branch Office will gladly answer any questions there may be about this equipment.

(2) The master clock is a very high-grade, accurate timekeeper and if properly installed and regulated, will give fine service for many years. It is the heart of the entire system and deserves to be treated as such. It should be properly serviced at least every two years by this Company's service experts. The movement is self-winding and when once regulated, should require no further attention.


(3) Hang the master clock on a screw or lag bolt, not less than 5/16" in diameter. Drill the hole for this screw or bolt so that when screwed into place, the outer end will be higher than at the point where it enters the wall. When the master clock is hung, it should have a tendency to slide back tightly against the wall. Do not attempt to hang the master clock upon a toggle bolt.

(4) If the master clock is arranged for flush mounting, it should be carefully set inside of the wall box and blocked into position so that the pendulum tip is directly in line with the center of the pendulum index scale. Screws can then be put through the sides of the case into the wall box to securely hold the clock in place.

(5) After the clocks is hung and the pendulum is installed, move the bottom of the case to right or left until pendulum tip is directly in line with the center of the pendulum index scale, hold in this position and after lowering one end of the pendulum scale, insert a 2-1/2" X #12 round head wood screw in the hole provided back of the scale, and make sure that the case is absolutely firm at the bottom. It may be necessary to mark the location of the bottom hole and remove the case from the wall in order to drill and plug the hole. Rawl plugs are suitable for this purpose. If the wall is of hollow tile or is surfaced with plaster over wire lath, it may be necessary to use a toggle bolt at the bottom.


(6) (a) Metal Bob, Wood Rod Type - Remove nut and stirrup on bottom of pendulum rod. Hold rod securely downward so that hook at top is toward the back, and slip bob over rod. (Bob should hang with spring on back at top.) Replace stirrup and turn on nut until top edge of bob is even with pencil mark across front of rod. Next, place hook on top of rod over the pin on the suspension spring in back of the movement near the top. Place the verge pin in position in the slot in the pendulum rod. Be careful not to lift or twist rod when in position on the suspension spring.

(7) (b) Invar Type - This pendulum is shipped fully assembled and it is only necessary to hang the rod on the suspension spring in back of the movement near the top. Do not untie the strings until the pendulum is in place since these help to keep the movable parts in their factory regulated position. Slip the fork of the verge lever over the pendulum rod. Be careful not to lift or twist rod when in position on the suspension spring. Hold movable bob while hanging pendulum on suspension spring. The red mark on the movable bob should line up with mark on the fixed bob. The red mark on the rod should be even with the top of the fixed bob.

(8) (c) Mercurial Type - This pendulum is shipped outside of the master clock case and must be assembled only after the clock is hung on the wall. Hang the rod on the suspension spring in back of the movement near the top being careful not to twist or bend the spring; then slip the fork of the verge lever over the rod. Next, fasten the two tubes of mercury into place with the knurled cap on top. Be careful not to change adjusting nuts "A" or "B", as these are carefully adjusted at the factory for proper regulation.


(9) A schematic wiring diagram is enclosed with these instructions and this should be carefully followed in making wiring connections to all equipment. Wire connecting terminals on the top of the master clock are numbered and corresponding numbers appear on the diagram. Take particular care that all wires are securely clamped under the binding screws. It is recommended that the switch in the rectifier be left in the OFF position until all wire connections are made to all equipment and the system is ready to start in operation. This will prevent any short circuits or scattering of the secondary clocks.


(10) First, see that all of the single-pole switches in the master clock are open. This disconnects the secondary clocks and program and prevents them from scattering. Next, throw the switch in the power rectifier to "ON" and press the strap key marked "WIND" in the bottom of the case, 54 times slowly. If there is no click of the winding mechanism when the key is pressed, it indicates that the wire connections have not been properly made or else fuses may be blown. Check the fuses in the rectifier and read the instructions inside of the rectifier door carefully.

(11) The correct method of starting any pendulum to swing is to grasp: (a) the adjusting nut on the metal bob pendulum, (b) the lower left-hand knurled nut on the mercurial pendulum, or (c) the pointer on the invar pendulum, with the fingers of the left hand, pull the pendulum to the left carefully until the pointer at the bottom is about division to the left of No. 2 on the pendulum index scale, and then release it at the correct time thereby permitting it to swing naturally. Do not "bat" the pendulum with the hand or cause it to swing excessively as this may damage the contacts or other parts of the movement.

(12) When necessary to stop the pendulum, it should be done with the second hand indicating somewhere between the 35th and 55th second after any minute in order to avoid continuous closure of contacts on the master clock movement. See that the second hand advances evenly at each swing of the pendulum; if it does not, turn the beat adjusting screw attached to the escapement  at the top of the movement. This should be turned slowly in one direction or the other until the movement of the second hand becomes uniform at each swing of the pendulum.

(13) When it is necessary to remove the dial from the master clock, care should be taken in replacing the hands. The second hand should be adjusted to point exactly to 60 at the top of the seconds beat circle and the minute hand directly over the proper minute mark at the instant the clock relay is energized. The pendulum will have swung to the left at this same instant. Do not attempt to adjust the second hand when it is in motion.

(14) In replacing the minute hand, care should be taken that the hour contact, which is the vertical one viewed through the second circle, moves over to the left and closes at approximately the 59th minute. If the minute hand is placed at any of the other three positions, the secondary clocks will reset at the wrong time. The minute hand on the master clock should never be turned backward. If the clock becomes fast, it should be stopped until correct time catches up with it, and then started again. It is very important that the minute hand be set exactly over a minute mark on the dial when the second hand is at the 60th second as otherwise the resetting impulse will come at the wrong time and cause the clocks to be either fast or slow.


(15) When ready to start the secondary clocks in operation, first make sure that the clock circuit switches, "Clocks 1, 2, 3, etc. or Clocks M", in the bottom of the master clock are closed, and then all clocks may be set forward by depressing and releasing the setting key marked "Set Key" in the bottom of the master clock case. When there is more than one circuit of clocks, a separate clock circuit can be set forward by opening all of the clock circuit switches in the bottom of the master clock, except the one in the circuit to be set ahead, and then operate the "Set Key" as before. Clocks will be set ahead one minute for each depression of the set key. Care must be tgaken not to press this key when the second hand on the master clock is near the 60 as this may cause a double impulse and scatter the secondary clocks. The "Set Key" must never be depressed rapidly and especially if the large dials are used. With small dials it can be pressed once a second, but with large dials the key should be held closed for a full second, and two to four seconds should elapse between operations. When a circuit is fast, open the switch controlling it, and leave it open until the clocks indicate the correct time. Then close the switch after the second hand has passed 60.

(16) Secondary clocks with dials up to and including 14" in diameter may be set separately by turning the hands forward or backward, provided that the hands are accessible from the front. If not, it is necessary to set the hands ahead by removing the cover from the movement and depressing and releasing the armature of the driving magnet. Care should be exercised in doing this, so that the fingers do not put the movement out of adjustment.

(17) On automatic reset systems, each secondary movement and the program clock use two sets of operating magnets -- one receiving minute impulses from the master clock for regular operation and the other receiving hourly impulses for resetting the clocks if necessary, once every hour. If all clocks are on time with the master clock, nothing will happen at the hourly impulse but in case any secondary or program clock is not more than 25 minutes fast or slow, it will be reset to the proper time. This hourly resetting impulse occurs every hour, between the 59th and 60th minutes, and brings the minute hand of all clocks to the 59th minute. This resetting applies to the program clock also in case one is used.

(18) A program impulse switch, "Program M", is provided in the master clock case so that it can be individually controlled, separately from the secondary clocks. Unless this switch is opened, the program clock will be advanced with the secondary clocks when the "Set Key" is operated.

(19) In addition to the regular setting key in the master clock, for advancing the secondary clocks and program, a reset key "Reset" is also provided for the entire system. A reset switch "Clocks R", is also provided for the clock system and also one "Program R" for the program so that this resetting impulse can be disconnected when desired. When a metal program is used, an additional reset key, "Reset Program", is used. (See Metal Disc PRogram Instructions, Bulletin No. 102.) Since several seconds are required for the minute hands of all secondary clocks to come to rest at the 59th minute, this reset key should be held closed for not less than 10 seconds and not less than 15 seconds, where large clocks are used (30" diameter dials or larger).


(20) A separate set of instructions for either the ribbon or the metal disc type of program machine is included with these instructions and this should also be carefully read for information in regard to these mechanisms. (Bulletin No. 101 for ribbon program and Bulletion No. 102 for metal disc).


(21) Practically all systems are arranged to operate on 24 V. DC and this voltage is obtained from the 115 V. AC 60 cycle power supply through a full-wave, dry-disc rectifier. A main AC disconnecting switch is provided on the rectifier for disconnecting the 24 V. DC when desired. The clock system will continue to operate only so long as the AC power is available. When this fails, the secondary clocks and program stop. When the power comes back on again, the system will start to operate and the secondary clocks will be slow by the amount of time the power has been off. Provided that the failure is not more than 25 minutes, all secondary movements and the program will be automatically reset to the proper time as indicated by the master clock on the next 59th minute. In case the power failure is longer than 25 minutes, the system must be manually set to the correct time as indicated above. The master clock will run for 50 minutes with the power off. If it has stopped, see Paragraph #10 for starting.


(22) When this type of power supply is installed, the same rectifier as used above is furnished, except that a special transfer relay is mounted in the rectifier cabinet to transfer the entire clock system to a reserve power unit, in case of AC failure. With these systems, a power failure signal bell is mounted in the master clock which gives a single stroke at the time the clocks operate, to indicate that the system is operating from the reserve power unit and that the AC power supply has failed. When this bell is heard, the system should be check immediately and the AC power restored as soon as possible. The reserve power unit is only for emergencies and should never be allowed to operate the system for long periods of time.


(23) Most rectifiers have a pair of terminals fed from the transformer secondary, arranged to deliver 24 V. AC for the operation of program bells, and wiring should be connected to these as indicated on the schematic diagram.


(24) Instructions for systems using this type of master clock will be given on a separate sheet. (See Bulletin No. 105)


(25) Instructions for systems using this type of master clock will be given on a separate sheet. (See Bulletin No. 106)


(26) All master clocks are completely set up at the factory and run for a regulating period of several weeks so that when ready for shipping, they are keeping accurate time. However, due to different conditions at the job, it may be found that further regulation is necessary after a week or more of operation, in which case proceed as follows.

(a) Metal Bob, Wood Rod Type - Turning the thumb nut at the bottom of the rod to the right raises the bob and makes the clock run faster.

(b) Invar Type - The upper part of the bob, "Fixed Bob", is loose on the rod, but is keyed to it, to prevent turning. The lower part, "Movable Bob", is threaded to the rod and may be raised or lowered by turning. The pointer is also threaded to the rod and is used as a lock nut against the lower part. To regulate, grasp the upper part of the bob in the left hand and rotate the lower part with the right. Turning the lower part to the right shortens the pendulum, rating the clock faster and turning it to the left rates it slower. In order to turn it to the left, it may be necessary to turn the pointer to the left slightly, also. The upper beveled edges of the lower part has 25 scale divisions and turning this one division with reference to the mark on the upper part, will affect the regulation approximately one second in 12 hours. The pendulum can be regulated without stopping it by carefully swinging it with the left hand at the normal speed.

(c) Mercurial Type - Turning the regulating nut "A" shorten the pendulum, rating the clock faster and to the left, lowers the bob rating the clock slower. This nut is marked with 50 divisions at its upper end and turning it two divisions will affect the regulation approximately one second in 12 hours. After clock has been fairly accurately regulated, by nut "A", finger regulation may be obtained by turning nut "b" either way with a pencil while pendulum is in motion. This nut "B" is a micrometer adjustment and one complete turn will affect the regulation only a fraction of a second in 24 hours.



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