Paragraphs

Claims

The variably timed transmission comprises three superposed concentric members :

the first member is the drive shaft [17] located in the inner section,

the second member is the sleeve [28] of gear [20] located in the outer section and

the third member is the sliding tube [32] located in the intermediate section between the two aforesaid members.

Said sleeve [28] is held in a bearing plate [15] by means of a suitable double-row angular contact bearing [16] mounted between the bearing plate [15] and sleeve [28].

Said bearing plate [15] is secured to the engine unit [1] so that the variably timed transmission forms a separate assembly with respect to the shaft [18] of the short-stroke crankshaft [5].

For this purpose , the variably timed transmission and the short-stroke crankshaft [5] are designed each with their own shaft [17] and [18].

The abuting ends of shaft [17] of the variably timed transmission and of shaft [18] of the short-stroke crankshaft [5] are provided with straight male splines and corresponding female splines, so as to permit their coupling within the engine unit [1] through an axial slide movement when the bearing plate [15] in engaged in an opening of the engine unit [1].

The bearing place [15] is centred with respect to shaft [18] of the short-stroke crankshaft [5], so as to permit sel-centering of shaft [17] with respect to shaft [18] , the latter also acting as a free bearing for shaft [17] when the bearing plate [15] is applied against the engine unit [1] ; such means permits the variably timed transmission to be removed from the engine unit [1] without having to remove the short-stroke crankshaft [5].

Claims