A Self-Winding Model 72
The Timex Model 74 movement is a new thin self winding watch which uses the basic construction of the Model 72. A new planetary gear winding system located on the dial plate provides a compact method of obtaining the necessary gear reduction between the self winding weight and the mainspring.
All the features of the Model 72 movement, for example removable cap jewels and permanently fixed pallet jewels, are also found in the Model 74 movement. The reserve power of the mainspring, when the watch is worn by a normally active person, is sufficient to run the watch for a full day.
Exploded View
The Model 72 list with the planetary winding parts added and the ratchet wheel renumbered.
Disassembly for Cleaning
Removing the Dial and Hands
Remove the sweep second hand. Do not remove the hour or minute hand.
The dial is clamped to the movement mounting ring by four tabs protruding from the outside of the dial. Straighten these tabs as indicated by the arrow and dotted lines in the illustration and remove the entire assembly.
Once the dial assembly is off there is no need for further dismantling unless severe contamination is present on the friction and cannon pinions. Should further dismantling be required, removal of the minute hand will free the friction and cannon pinion assembly. The friction pinion is held in the cannon pinion by a snap fit.
Removing the Rotor
Invert the movement so that the rotor is facing you and remove the two rotor frame screws.
Lift the rotor assembly slightly to free the dowels which position it. Since the rocker arm fits between the rotor frame and the rotor weight assembly, the rotor weight must be removed by sliding it along the movement plate until it is free of the rocker arm.
Removing the Mounting Ring
Before removal of the mounting ring, the mainspring power must be fully let down. Grasp the crown in the fingers of one hand and move the click out of engagement with the ratchet wheel. Let the crown revolve slowly in the fingers, being careful not to let the crown slip.
After the mainspring is fully let down, remove the four mounting ring screws. Next remove the mounting ring ratchet wheel, planet pinion assembly and click.
The Small Mounting Ring Screws
The location of the four small mounting ring screws on the movement.
What Follows the Model 72
Proceed as directed for the Model 72 movement.
Proceed as directed for the Model 72 movement.
Proceed as directed for the Model 72 movement.
Proceed as directed for the Model 72 movement.
Reassembly procedures for the balance, the position of the hairspring and positioning of the sweep second hand are given on page 72.8. All four are covered in the Model 72 guide.
Cleaning & Lubrication
After disassembly of the sweep second hand, dial, rotor, mounting ring, planetary gear system, wind and set mechanism, minute wheel, click, balance and cap jewels, the movement is ready to be cleaned. The same instructions for cleaning as given for the Model 72 movement apply to the Model 74.
The same re-oiling instructions given for the Model 72 movement apply to the Model 74. In addition, all moving parts of the self winding and planetary gear system should be oiled. A drop of oil should be applied between the slip tail and the barrel.
Use the disassembly procedure for the Model 74 and 72 movements as a guide for reassembly.
Helpful Hints
- Oiling. When oiling the balance “V-conic” jewel bearing in the movement plate, to facilitate the precise entry of the oil to the bottom of the cup, remove the balance screw from the dial plate and insert the oiler through the dial plate balance screw hole.
- A drop of oil applied to both sides of the stem wind pinion before assembly will hold the pinion and its bridges together, thus facilitating assembly should complete dismantling of the movement be necessary.
- Examine the action of the rotor on the winding frame. Be certain the staking is secure and that the rotor is free to make a complete revolution without interference. Check that the spring which holds the movement in the bezel is properly located in its groove.
- Check the freeness of the rocker arm and the clicks which are attached to it. Check that the yoke of the rocker arm slides freely on the cam attached to the self-wind weight without interference.
- Check the action of the winding ratchet wheel. Each rotation of the rotor should move this wheel forward approximately 6 teeth.
- Check the action of the mainspring and the barrel. The mainspring should have 6 to 8 full turns before the slip tail begins to revolve in the barrel.