Improved 176 small cylinder diameter diesel engine

The utility model discloses an improved 176 small cylinder diameter diesel engine. The utility model is characterized in that the structure of the flywheel end of the main neck journal of the crankshaft is provided with a rolling bearing; the structure of the timing gear end of the main neck journal of the crankshaft, namely a speed control end, is provided with a sliding bearing. Oil passage holes orderly communicated with each other and with the main oil gallery of the machine oil pump in a lubrication system are orderly arranged between a machine body sliding bearing crankshaft and a connecting rod bearing shell. The piston travel of the utility model is less than or equal to 65 mm, and the inside diameter of the cylinder liner is less than or equal to 76 mm. Compared with the prior art, because the timing gear end of the main neck journal of the crankshaft is provided with the sliding bearing, the lubricating form is pressure lubrication provided by the machine oil pump; the lubricating effect of the sliding bearing is ensured; especially the big lubricating oil pressure in the oil passage hole of the connecting rod bearing shell is guaranteed. Under the declared working condition, the pressure of the lubricating machine oil can be 0.2-0.3 MPa; the lubricating effect is reliable, and the service life of the connecting rod bearing shell and the crankshaft is extended.