Reducing Transportation Cost by Means of Engine Design 290010
THE 4¼ x 5½-in. six-cylinder motorcoach engine built by his company is used by the author as an example of the methods governing its design, the main controlling factors being that regularly recurring maintenance operations should come in groups, so that the operator can systematize his shop-work; that all units should be interchangeable; that any operation should be completed by a trained crew in a maximum time of 2 hr.; and that removal of the engine from the chassis should almost never be necessary except for work on the main bearings and for crankshaft regrinding.
Some of the engineering features that illustrate the adherence to these governing principles in working out details of design are the cylinder-head unit, complete with valves, camshaft, valve-operating mechanism and governor, which is interchangeable on all engines of a given series; interchangeable cylinder-blocks merely clamped between the crankcase and the cylinder-head; absence of bosses on the cylinder-barrels and extension of studs from the crankcase entirely through the cylinder-block to the cylinder-head; connecting-rods and pistons removable through handholes below each two adjacent cylinders; a force-feed lubricating system which includes an oil-filter and a system for distilling diluent out of the oil, which is circulated over the cylinder-head; and a two-way carbureter air-intake for taking air at atmospheric temperature from outside the engine hood or, in cold weather, from an exhaust stove.
The author gives his reasons for preferring the overhead-valve engine for motorcoach service, describes the special pistons used and the connecting-rod production processes, and makes statements regarding the quality of the materials used in the more important parts of the engine.