A thin self-winding watch built on the construction of the Model 24, with a new planetary gear winding system on the front frame. It is the base that the Model 33 was later built on.
Self-Winding13 LigneModel 24 Base
Factory Service Manual · Model 31 · Dial Side & Movement Side
Ligne13
Diameter29.08 mm
Diameter (inches)1.145 in
TypeSelf-winding
Built onModel 24 construction
ManualService Manual · Model 31
Height5.50 mm
Jewels0
EscapementPin lever
Beat rate18,000 bph
Power reserve38 h
Height, jewels, escapement, beat rate and power reserve: ranfft.org
A Thin Self-Winder
The TIMEX Model 31 movement is a new thin self winding watch which uses the basic construction of the Model 24. A new planetary gear winding system located on the front frame provides a compact method of obtaining the necessary gear reduction between the self winding weight and the mainspring.
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.
Timex found that the best method of cleaning is with only the sweep second hand, dial, mounting ring, planetary gear system and balance removed. The cleaning fluid, while removing any contamination from the movement, will also remove oil from the gear train, pivots and holes.
Note: If further dismantling is required, follow the instructions for the Model 24 movement.
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 the movement there is no need for further dismantling of the dial assembly 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.
Fig. 31.3 · Dial & hands
2 · Removing the Rotor
Invert the movement so that the movement plate 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.
Caution: Any attempt to lift the weight before it is free of the rocker arm will result in damage to the movement.
Fig. 31.3 · Removing the rotor
3 · 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 letting the power of the mainspring down, remove the four mounting ring screws. Next remove the mounting ring ratchet wheel, planet pinion assembly and click.
Fig. 31.4 · Removing the mounting ring
4 · Crown, Stem and Balance Wheel
For the crown and stem, proceed as directed on page 24.4 for the Model 24 movement.
For the balance wheel, proceed as directed on page 24.5 for the Model 24 movement.
Fig. 31.4 · Mounting ring screws
Cleaning & Lubrication
Lubricant change, June 1974: Timex Service Bulletin No. 111 replaced the factory oil for this model. Moebius Synt-A-Lube oil is used instead of Elgin M56B oil or Tenneco #415 oil. (It supersedes Bulletin No. 108.)
After disassembly of the sweep second hand, dial, rotor, mounting ring, planetary gear system, click and balance, the movement is ready to be cleaned. The same instructions for cleaning as given for the Model 24 movement apply to the Model 31. Care should be exercised to insure complete cleaning of all self winding parts.
The same reoiling instructions given for the Model 24 movement apply to the Model 31. In addition, all moving parts of the self winding and planetary gear system should be oiled.
Caution: As noted on the Model 24 movement, the mainspring is permanently lubricated and should not be oiled.
Reassembly
Use the disassembly procedures for the Model 31 and 24 movements as a guide for reassembly. Reassembly procedures for the balance wheel, position of the hairspring and positioning of the sweep second hand are given on page 24.7.
Helpful Hints
Oiling. When oiling the movement plate balance cup, to facilitate the precise entry of the oil to the bottom of the cup, insert the oiler through the dial plate balance screw hole before the balance screw is assembled.
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 5 to 6 full turns before the sliding tail begins to revolve in the barrel.
This guide is based on the original Timex factory service manual for the Model 31 movement.
