Timex M85 Movement — Service Manual & Teardown

A Calendar on the Model 84

The Timex M-85, caliber 880/881, is a 13½ ligne electric calendar watch movement. The basic movement is the same as the M-84, however a sophisticated calendar mechanism has been added to the dial side. The calendar mechanism is unique in that it is instantaneous, taking only seconds to switch the date, and because it provides a dot as an A.M./P.M. indicator along with the date numeral.

When the date numeral is viewed through the dial window, this dot is displayed either above or below the numeral. If the dot is below the numeral it indicates A.M.; if above, it indicates P.M.

Setting the date: The date can be set manually by rotating the hands. For quick date setting, move the hands counterclockwise to approximately 9:00 o’clock and then clockwise to just past 12:00 o’clock.

Note: The movement underneath is the Model 84 and this manual does not repeat its servicing. See the Model 84 guide for the electric movement, its contact system and its train.

Timex Model 85, movement side — Dial side

Exploded View

Everything below the numbered parts is the Model 84 electric movement.

How the Date Switches

The Drive

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The pin on the date cam is driven by the hour wheel. At 12:00 the lobe of the cam is in a position to allow the date indexing lever to drop off, move to the right, engage and advance the date ring. Since the indexing lever is under spring tension by means of the indexing spring, this action is instantaneous.

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The click (2576) holds the date ring in position. This click is also under spring tension by means of the indexing spring.

The date indexing lever, date click, date ring, date cam and indexing lever spring

Fig. 85.3 · Calendar Mechanism

Because the date cam is driven directly by the hour wheel, instead of through a reduction gear as in most watches, the advancing action of the date ring occurs at both 12 midnight and 12 noon. The shape of the teeth on the index lever and date ring is such that each indexing will not move the date ring forward one full space: only three quarters of a full space at 12 midnight, and one quarter of a full space at 12 noon. In this way Timex has been able to provide the A.M./P.M. indicator on the date ring.

Midnight to Noon

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From 12 midnight to 12 noon the date is displayed in the window with a small dot below the numeral.

The date window showing the numeral with the dot below it

Fig. 85.3 · 12:00 Midnight to 12:00 Noon

Noon to Midnight

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At 12 noon, instead of switching to a new numeral, the date ring only indexes a quarter space: the numeral moves to the lower portion of the window and a new dot appears above it, indicating P.M.

The date window showing the numeral moved down with the dot above it

Fig. 85.3 · 12:00 Noon to 12:00 Midnight

Disassembly

Getting the movement out of its case first? Case types and dust seals

a

Date cam 2552/1

b

Second date holder 2535/2 with screw 52535/2

c

Date click 2576

d

Date indexing spring 2575

e

First date holder 2535/1 with screw 52535/1

f

Date indexing lever 2539/1

g

Date ring 2557/1

The hour hand: the hour hand is placed in a precise angular position with the slot in the hour wheel so that date switching will occur at 12 o’clock. If it becomes necessary to remove the hand from the hour wheel, note this position so the hand can be replaced in the same position.

Cleaning & Lubrication

All cleaning and lubricating points indicated for the M-84 should be followed for the M-85. In addition, lubricate the bearing of the date cam 2552/1 as well as the outer edge which bears against the date indexing lever. Lubricate the guide pins of the date indexing lever 2539/1, and the bearing and working surfaces of the date click. Lubricate the working surface of the date indexing spring 2575.

Caution: Since the watch contains permanent magnets, no attempt should be made to demagnetize it.

TheModel 85