Abstract: A plastic fuel tank having polyethylene layers is disclosed. The polyethylene layer positioned as the outermost layer of the plastic fuel tank is a high-density polyethylene layer admixed with an ultraviolet inhibitor for minimizing transmission of ultraviolet light.

Abstract: A plastic fuel tank is disclosed including polyethylene layers laminated respectively onto an upper surface and a lower surface of an ethylene/vinyl alcohol layer for preventing fuel seepage. The outermost polyethylene layer laminated onto the upper surface is a high-density polyethylene layer colored black so as to minimize transmission of ultraviolet light.

Abstract: A plastic fuel tank is disclosed including polyethylene layers laminated respectively onto an upper surface and a lower surface of an ethylene/vinyl alcohol layer for preventing fuel seepage. The outermost polyethylene layer laminated onto the upper surface is a high-density polyethylene layer colored black so as to minimize transmission of ultraviolet light.

Abstract: A plastic fuel tank having polyethylene layers is disclosed. The polyethylene layer positioned as the outermost layer of the plastic fuel tank is a high-density polyethylene layer admixed with an ultraviolet inhibitor for minimizing transmission of ultraviolet light.

Abstract: A vertical internal combustion engine E has a crankshaft 18 enclosed in a crank chamber 20, a belt-drive transmission mechanism 50 held in a belt chamber 63 and including a rubber belt 53 for transmitting power of the crankshaft 18 to a camshaft 24 in a valve train 23, and a transmission case 60 defining the belt chamber 63. The belt chamber 63 communicates with the crank chamber 20 by way of vent holes 70 and 71, the transmission case 60 is provided with an internal wall Wi disposed between the vent holes 70 and 71 and the belt 53 in the belt chamber 63 to deflect the flow of an oil-containing gas flowing from the crank chamber 20 into the belt chamber 63 such that the oil-containing gas flows in directions deviating from a direction toward the belt 53. The belt 53 is lubricated with oil in the oil-containing gas. The belt 53 is prevented from being excessively exposed to the oil-containing gas from the crank chamber 20 to extend its life.

Abstract: A vertical internal combustion engine includes a crankshaft enclosed in a crank chamber, a belt-drive transmission mechanism held in a belt chamber and including a rubber belt for transmitting power of the crankshaft to a camshaft included in a valve train, and a transmission case defining the belt chamber. The transmission case has a lower case between the crank chamber and the belt chamber. The belt has a part extending over the crank chamber, and the lower case is disposed to screen the part of the belt from the crank chamber. The belt is lubricated by oil in oil-containing gas from the crank chamber. Thus the oil containing gas is prevented from excessively contacting the rubber belt, so that the life of the belt is extended.

Abstract: A vertical internal combustion engine E is incorporated into an outboard motor or the like. The vertical internal combustion engine E includes a crankshaft 18 enclosed in a crank chamber 20, and a belt-drive transmission mechanism 50 including a rubber belt 53 for transmitting power of the crankshaft 18 to a camshaft 24, and held in a belt chamber 63. The belt chamber 63 is isolated from the crank chamber 20 by a lower case 61 of a transmission case 60 holding the belt-drive transmission mechanism 50 therein such that the flow of an oil-containing gas from the crank chamber 20 deviates from a direction toward the belt 53. The belt 53 is lubricated with oil injected concentratedly into the belt chamber 63 through jet nozzles 80 disposed in the belt chamber 63. Thus the excessive exposure of the belt 53 to the oil-containing gas from the crank chamber can be avoided, the life of the belt can be extended and the belt is lubricated properly.

Abstract: A vertical internal combustion engine E has a crankshaft 18 enclosed in a crank chamber 20, a belt-drive transmission mechanism 50 held in a belt chamber 63 and including a rubber belt 53 for transmitting power of the crankshaft 18 to a camshaft 24 in a valve train 23, and a transmission case 60 defining the belt chamber 63. The belt chamber 63 communicates with the crank chamber 20 by way of vent holes 70 and 71, the transmission case 60 is provided with an internal wall Wi disposed between the vent holes 70 and 71 and the belt 53 in the belt chamber 63 to deflect the flow of an oil-containing gas flowing from the crank chamber 20 into the belt chamber 63 such that the oil-containing gas flows in directions deviating from a direction toward the belt 53. The belt 53 is lubricated with oil in the oil-containing gas. The belt 53 is pre-vented from being excessively exposed to the oil-containing gas from the crank chamber 20 to extend its life.

Abstract: A vertical internal combustion engine E is incorporated into an outboard motor or the like. The vertical internal combustion engine E includes a crankshaft 18 enclosed in a crank chamber 20, and a belt-drive transmission mechanism 50 including a rubber belt 53 for transmitting power of the crankshaft 18 to a camshaft 24, and held in a belt chamber 63. The belt chamber 63 is isolated from the crank chamber 20 by a lower case 61 of a transmission case 60 holding the belt-drive transmission mechanism 50 therein such that the flow of an oil-containing gas from the crank chamber 20 deviates from a direction toward the belt 53. The belt 53 is lubricated with oil injected concentratedly into the belt chamber 63 through jet nozzles 80 disposed in the belt chamber 63. Thus the excessive exposure of the belt 53 to the oil-containing gas from the crank chamber can be avoided, the life of the belt can be extended and the belt is lubricated properly.

Abstract: A vertical internal combustion engine E includes a crankshaft 18 enclosed in a crank chamber 20, a belt-drive transmission mechanism 50 held in a belt chamber 63 and including a rubber belt 53 for transmitting power of the crankshaft 18 to a camshaft 24 included in a valve train 23, and a transmission case 60 defining the belt chamber 63. The transmission case 60 has a lower case 61 between the crank chamber 20 and the belt chamber 63. The belt 53 has a part 53a extending over the crank chamber 20, and the lower case 61 is disposed to screen the part 53a of the belt 53 from the crank chamber 20. The belt 53 is lubricated by oil in oil-containing gas from the crank chamber 20. Thus the oil-containing gas is prevented from excessively contacting the rubber belt, so that the life of the belt is extended.

Abstract: A cam gear is formed from a resinous material containing 100 parts by weight of polyamide and 5 to 20 parts by weight of modified polyolefin.