Vedeneyev M-14P, Maintenance Manual

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The timing mechaniam comprises a cam plate, a cam plate drive, tappet guide bushings, tappets with
rollers, push rods in casings, valve rockers with adjustment screws and rollers, inlet valves and exhaust
valves with springs, plates and retainers.
The valve mechanism is described in Section 2.1. The schematic diagram of the timing mechanism is
given in Pig. 6.
The cam plate is rotated from the crankshaft through a gear train. The cam plate lobes contacting the
tappet rollers move the tappets in the guides away from the crankshaft axis. The tappets move the push rods
installed between the tappet seats and adjustment screws of the valve rockers. The push rod displaces the
front arm of the rocker away from the crankshaft axis, the rear arm approaches to it thrusting with the roller
against the end of the valve stem, compresses the valve springs and opens the valve to admit fresh mixture
and release exhaust gases. The valve closure is determined by the profile and location of the lobes on the
cam plate.
The cam plate (Ref. Pig. 7) is a steel disk with a hub, having two rows of lobes on the outer cemented
surface: four lobes per row. The front row of the lobes serve the rollers of the inlet valve tappets, the rear row,
the rollers of the exhaust valve tappets. A bronze bushing locked against turning with two retainers is pressed
in the hub. Provided on the inner surface of the cam plate is an internal gear rim meshing with the gear rim of
the intermediate timing shuft.
The cam plate drive (Ref. Pig. 8) comprises drive timing gear (1), intermediate gear (7), intermediate
timing shaft (4), two ball bearings (6) and (9) and other minor components..
The drive gear is installed on the end of the crankshaft front section and is secured against turning
with a sunk key.
Intermediate timing gear (7) is made of steel and has an outer gear rim and a hub. The inner surface
of the hub is made with rectangular splines to install intermediate timing shaft (4).
Steel intermediate timing shaft (4) consists of a gear rim made integral with the hollow shaft
supported on two ball bearings.
The shaft middle portion is splined externally to receive gear (7) and has two locating cylindrical seats
for the ball bearings. The front ball bearing outer race is pressed in the seat of the crankshaft thrust ball
bearing front cover. The rear ball bearing outer race is installed in the seat of the timing drive cover. When
assembled the shaft carries, starting from the gear rim: rear ball bearing (6), intermediate gear (7), bushing
(8) with front ball bearing (9), adjustment washer (10) and drive bevel gear (11) of the speed governor drive,
which is secured on the shaft by Woodruff key (5). All the parts on the shaft are tightened with nut (13) and
safetied with lock (12).
The cam plate rotates opposite to the crankshaft. The engine timing is ensured by getting the cam
plate drive and the cam plate by the timing marks and do not require special adjustments.