Camshaft drive mechanism

An internal combustion engine of the type comprising twin cylinders arranged in a vee in a plane normal to the crankshaft of said engine and having a crankcase including a camshaft drive mechanism comprising a first camshaft for actuating inlet and exhaust valves of one of said cylinders and a second camshaft for actuating inlet and exhaust valves of the other of said cylinders, which camshafts rotate on axes parallel to the axis of said crankshaft and with said camshafts being driven by a gear on said crankshaft which engages a primary gear on said first camshaft with an adjacent secondary gear on said first camshaft imparting counter-rotation on said second camshaft via an identical secondary gear on said second camshaft;

• and wherein said crankcase casting includes tappet blocks as integral components of said casting.

An internal combustion engine of the type comprising twin cylinders arranged in a vee in a plane normal to the crankshaft of said engine and including a camshaft drive mechanism comprising a first camshaft for actuating inlet and exhaust valves of one of said cylinders and a second camshaft for actuating inlet and exhaust valves of the other of said cylinders, which camshafts rotate on axes parallel to the axis of said crankshaft with said camshafts being driven by a gear on said crankshaft which engages a primary gear on said first camshaft with an adjacent secondary gear on said first camshaft imparting counter-rotation on said second camshaft via an identical secondary gear on said second camshaft;

• wherein said camshaft drive mechanism is housed in a cam chest having a back wall with bearings therein for ends of said first and second camshafts, and said cam chest has a cover which includes bearings for the other ends of said first and second camshafts;
• longitudinal movement of said first camshaft is prevented by thrust washers between steps on said camshaft and said bearings;
• and longitudinal movement of said second camshaft is prevented by a thrust washer between a step on said camshaft and said back wall bearing therefor and a thrust interface within the housing for the bearing for said camshaft in said cam chest cover.