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THIS paper outlines the advantages and disadvantages of present-day hydraulic systems. Included in the discussion are: the blocked return line system for single-acting cylinders, the blocked pump inlet, and the basic open-center-valve system. More advanced designs mentioned are: open-center-valve systems with cylinders in series and with parallel cylinders, close-centered valve systems with pressure regulator, and the central hydraulic and accumulator systems. The author points out that the advantages and disadvantages of each system depend to a great extent upon the design in which it is used.

DATA presented in this paper show temperature-time diagrams obtained from mufflers mounted on trucks which were traveling over their regular routes. Using these temperature data, specimens made of possible muffler materials were subjected to laboratory tests. A wide range of possible muffler materials and gas composition were covered in these tests. Results of the tests indicate that under long-run heavy-duty truck service, muffler failure occurs primarily because of high metal temperatures and that coated mild steel showed the most promise of longer muffler life.

The John Deere Waterloo Tractor Works, as manufacturers of farm tractors, does not manufacture oil seals. We rely on the manufacturers of oil seals for design assistance. After establishing the initial design, laboratory and field tests are required for verification. One of the seal applications is on the crankshaft which must keep crankcase and transmission lubricants separated. Reliability and long life are imperative. Alertness as to the effect of detail changes on seal life is necessary to maintain long service life. The front wheel bearing seals may be subjected to submersion in water and mud. Packing, lip and face type seals have been tested with the face type proving the most rugged, although the most costly of the three types. A problem of design and space which was encountered in a hydraulic pump was overcome by design changes in the seal and in the pump. Constant vigilance on assembly methods and tool maintenance is a requirement to keep quality level high.

Railroad diesel locomotives have been powered with high grade all-distillate type fuels since their introduction. Such fuels have given excellent over-all performance. Recently, stationary locomotive tests conducted on the New York Central Railroad have indicated that a residual-distillate type fuel of 300 SSU viscosity at 100°F. gives satisfactory operation in an EMD F-7 freight locomotive equipped with a 567 B-16 engine when used in conjunction with a dual-fuel system. It is further indicated that the dual-fuel system appears practical for railroad operation. The use of the dual-fuel system was found to be necessary because operation with residual-distillate type fuel at the lower throttle positions was unsatisfactory. Distillate fuel is there fore required in these throttle positions. A field test is now in progress on the EMD F-7 test locomotive equipped with a dual-fuel system and using 300 SSU at 100°F. viscosity residual-distillate type fuel.

One of the prime factors on which John Deere tractor business was established was that of designing for low operating cost. In keeping with this policy, the Model 70 Diesel tractor was introduced in November, 1954. The Diesel engine is of the direct injection type. It has two cylinders with bore of 6-1/8 and stroke of 6-3/8 inches. Rated engine speed is 1125 rpm. The engine develops approximately 50 observed belt horsepower. Specific fuel consumption is approximately 15% less than that of the average competitive farm tractors based on Nebraska Tractor Tests. Starting of the Diesel engine is accomplished by an auxiliary gasoline engine.

HEAVY-DUTY rear axles are analyzed in this paper - the first L. Ray Buckendale Lecture to be delivered. The author presents a practical method of evaluating heavy-duty rear axles, with emphasis on performance and axle ratio. The major part of the paper is devoted to a discussion of the four functions of rear axles, as follows: (1) To carry the load, (2) to transmit driving torque, (3) to allow differential action, and (4) to help stop the vehicle.

SINCE world war II, integral implements have become increasingly popular. According to the author, this ever-increasing popularity of integral instruments over the corresponding towed type can be attributed to the following factors: 1. Greater maneuverability of tractor and implement combination. 2. Better transporting characteristics of tractor and implement combination. 3. Lower-cost implements. 4. Ease of attachment and control. An implement designer’s viewpoint on tractor hitches and hydraulic systems is presented here. The author hopes that it will help to assure that tractors of the future will have common implement-to-hitch attaching points, so that a tractor may be used with a number of different makes and sizes of integral implements. He also points out that certain performance features are needed to make integral instruments even more popular.

TORQUE converters have many advantages for industrial and commercial vehicles. Some of those listed by the author are: 1. Smooth acceleration. 2. Engine need not be declutched when it is unloaded or idling. 3. More horsepower delivered at low output speeds and during acceleration, compared with conventional transmissions. 4. Operator mistakes of improper gear selection and missing of shifts are reduced to a minimum. 5. Load held to power source at all times. 6. Damping out of engine torsional vibration. 7. Increased life for drive train beyond transmission. 8. Cushioning of shock loads during starting and shifting, and of sudden increases in load.

THE case for the operator of the heavy-duty truck is considered in this paper. The author points out that the average driver feels that standard truck components are being assembled without regard for specific problems which must be met and solved on the road. An objective look at torque-converter transmissions in use indicates the serious need for specific study of truck applications. The author describes the operation of logging and ore trucks in relation to loads and roads. He also gives performance data on short hauls handled by one driver, and on long runs where as many as 20 different drivers are required. He states that trucks and related rubber-tired vehicles present one of the largest potential markets available to the torque-converter transmission manufacturer if he will but design for the specific needs of that market.

RESULTS covering a year of test runs with the experimental gas turbine-powered motor truck, currently being developed by Boeing, are presented in this paper. Performance and operating characteristics are compared with those of heavy-duty diesel trucks, including results of fuel consumption tests, cooling tests, noise reduction progress, and transmission requirements. Mechanical engine troubles are recounted, together with a description of some of the engineering methods used in determining causes and corrections. The writer concludes that while neither fuel consumption nor wheel life of the turbine engine can be considered satisfactory in view of the tests, immediate prospects for needed improvement are excellent. In other respects the turbine engine is described as being already equal or superior to existing truck powerplants.