Gear backlash control for an opposed-piston engine

An opposed-piston internal combustion engine comprising:

• a gear train comprising an arrangement of gears coupling at least one crankshaft to an output drive;
• an oil providing system comprising an oil source;
• and
• a backlash reducing gear in the gear train, the backlash reducing gear comprising:
• a first gear with gear teeth and a recess for receiving oil;
• a second gear with teeth and a protrusion for fitting and moving within the recess in the first gear;
• a gear post on which the first gear and the second gear a mounted, the first gear and second gear configured to rotate about the gear post;
• an oil groove formed between the first and second gear, the oil groove in fluid communication with the recess;
• an oil inlet in fluid communication with a source of oil and the recess;
• an oil leak orifice in fluid communication with the oil groove and/or the recess;
• and
• a check valve in fluid communication with the oil inlet and the recess, the check valve configured to maintain a static hydraulic pressure within the backlash reducing gear at a level that maintains minimal backlash between the backlash reducing gear and at least one adjacent gear in the gear train,
• in which the oil inlet, oil groove, and recess form an oil flow path that is configured such that when the backlash reducing gear is in use, oil flows along the oil groove so that hydraulic pressure is exerted on all sides of the protrusion.