The fuel injection advance clutch is used to ensure economical operation of the engine at various speeds
When the crankshaft speed increases, it automatically increases the advance angle and thus provides sufficient time for fuel combustion, and when the speed decreases, it reduces this angle.
The coupling consists of two half-couplings: leading 1 (Fig. 1) and driven 13.
The driven half-coupling 13 is fixed on the conical surface of the front end of the fuel pump camshaft with a key and a nut with a washer, the driving pull-coupling 1 - on the hub of the driven half-coupling (can be rotated on it).
A housing 5 is screwed onto the driven half-coupling, which combines the parts of the clutch.
Loads 11 are loosely put on the fingers pressed into the driven coupling half.
Springs 8 hold the loads against the bushing 3. With this bushing, the drive half-coupling is loosely put on the cylindrical protrusion of the driven half-coupling.
Spaces 12, mounted on axles, made integral with the coupling half, are located between the fingers of the loads and their curved surfaces B.
The torque from the injection pump drive is transmitted to the drive coupling half 1, which rotates the driven coupling half 13, mounted on the toe of the injection pump camshaft, through spacers 12, weights 11 and axles 16 of the weights.
At a low crankshaft speed, the loads under the action of springs 8 are in the state reduced to the stop in the sleeve 3, and the driven half-coupling occupies a certain position relative to the leading one.
As soon as the crankshaft speed starts to exceed 1200 rpm, the resulting centrifugal forces of the loads 11 exceed the forces of the pre-compressed springs 8. As a result, the loads begin to diverge, turning on the axes 16.
The spacers 12 turn around their axis under the action of the fingers moving apart together with the weights.
By resting the profile surface against the curved surface and sliding along it towards the center, the spacers push the loads in the direction of rotation.
The driven coupling half, together with the pump shaft, turns in the direction of rotation of the coupling, increasing the fuel injection advance angle.
At the rated speed, the weights diverge to the stop, providing the largest angle of rotation of the coupling halves, equal to 4°30, which corresponds to an increase in the installation angle (with the engine off) of the fuel injection advance by 9° of the crankshaft rotation.
When the speed of the shaft decreases, the loads approach each other under the action of springs 8, reducing the lead angle.
To lubricate the friction surfaces of the coupling, 0.16 liters of engine oil is poured into it through the holes in the housing, closed with plugs.
Under the action of centrifugal forces, oil flows to all rubbing surfaces of the parts, and the most loaded interfaces (spacer - surface B of the load, load - axle, spacer - axle) are in the oil bath.