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In order to determine the operational characteristics of human pedal force, a driving simulator consisting of a driver's seat, pedals, analog computer, double gun synchroscope, etc., was developed. The driver was asked to guide the spot representing the controlled variable using the spot as a target. A simple transfer function to match the test results was derived and the effect of parameters on the constants in this function was analyzed. This experiment established that a pedal force of 200 daN seemed best for control.

After using an analog computer and a mechanical substitution system to determine if the project was possible, a remote control ground vehicle was designed and constructed which would follow a predetermined course at a given speed to test the handling characteristics of vehicles and to conduct crash tests safely. The vehicle is guided visually via onboard TV. Data are fed back by 6-channel FM, while 4-channel FM serves to transmit commands to servo motors in the unmanned vehicle. Except for a cathode ray tube, all onboard control instrumentation is crashproof, and a self-contained power source provides for fail-safe braking.

The use of a computer-generated vehicle mission simulator has made it possible for truck operators and manufacturers to select a horsepower-to-weight ratio to fulfill the requirements for operation over a known terrain. This practical presentation shows several specific applications of the procedure and offers some conclusions drawn from those applications.

Three investigations are reported which clarify the mechanism of exhaust hydrocarbon (HC) emission and suggest new ways to reduce these emissions from reciprocating, 4-stroke, spark-ignition engines. The work was carried out on an engine using the sealed ring-orifice (SR-O) piston, which effectively eliminates exhaust HC emission caused by the piston-bore-ring crevice. This reduces HC emission substantially, making other effects more apparent. In the first investigation, exhaust HC concentrations were unchanged when the engine was run first with oil and then water in the crankcase. This means that oil did not contribute to exhaust HC emission in the SR-O engine. In the second investigation, small patches of simulated deposit attached at different locations in the combustion chamber caused exhaust HC concentration increases which varied by a factor of 10, depending on deposit location.

The deterioration of secondary ignition wiring life on today's internal combustion gasoline engine has created many maintenance problems in the field. The mandatory use of TVRS (resistance wire) has amplified these problems and made them more difficult to solve. The solution does not lie solely with wire design-engine application, engine design, and component selection and location are also important factors. THE LIFE SPAN of the secondary wiring used on gasoline automotive engines dropped dramatically with the introduction of resistance-type wire which is commonly referred to as TVRS wire. The TVRS wire was introduced to suppress ignition interference in accordance with SAE specifications, and to meet the requirement of Public Law 200 passed in October 1951. The TVRS wire was also intended to reduce spark plug electrode erosion. While both of these missions were accomplished, in most cases the wire had a very short life.

A review of the long-standing highway truck ride problem and conventional solutions emphasizes an increased usage of suspension seats to isolate the driver from predominant cab vibration. A novel new suspension seat (Hydra-Flex) features an articulated linkage which conforms to similar kinematics as natural motion of the human body. Further, this linkage inherently provides an action which cancels the characteristic back-slapping motion of truck cabs. Numerous inherent advantages over conventional designs of suspension seats are disclosed, and these features are attributed to the “bionics” principle which is involved.

Increasing underhood temperatures and decreasing availability of vacuum, indirectly caused by more stringent safety and emission control regulations, brings the possibility of central hydraulic systems closer. However, as the central system fully evolves, equipment manufacturers indicate that they expect a transition step, where the same fluid will be used in both the power steering and power braking systems. With the expected demands on fluids to be used in such systems increasing, Dow Corning has initiated the development of a silicone candidate, based on the most readily available silicone fluid, dimethylpolysiloxane. The recent advances in lubrication technology, information on compatibility with presently used materials, and the inherent physical and chemical properties which allow a silicone fluid to be a serious candidate for such usage, are presented.

A new and different seat suspension suitable and advantageous for off-the-road and highway vehicles is presented. Contributing to a comfortable ride for the operator are several proved features, to which have been added three new and unique features. The seat suspension is an air-oil cushioning system to which has been added a servo-linkage to operate a two port hydraulic valve; the servo-linkage being tied to the vertical seat motion. The new, unique features are: 1. Unlimited range of adjustment of seat vertical position to suit the individual operator, assuring him of easy access to the brake pedal, good vision, and comfort, regardles of his particular body dimensions. 2. At any vertical seat position the operator chooses, automatic adjustment for the weight of the operator. 3. Clearance between the front edge of the cushion and the rim of the steering wheel, once set to the operator's liking, is maintained, including the time while the operator is dismounting and remounting.

A different approach to the study of drivetrain cost comparisons is presented, using 175 units operating within two fleets. Engine, transmission, clutch, driveshaft, universal joint, etc., were identical, item for item; the exceptions being identical brake types but different manufacture and differences in the manufacture of chassis. All units were serviced by the same mechanics. Use of a data bank by the mechanics gave a true cost/mile for the two fleets compared, and showed that good record keeping would provide fleet managers continued benefits.

Improved power brake booster designs and systems with redundant capabilities are anticipated to be required as a result of the new safety regulations for improved stopping distances, and indirectly, as the result of the new emission controls because of the potential loss of vacuum availability and increased underhood temperatures. In early 1968 it was becoming obvious to certain brake engineering groups that a new brake booster system with reserve capabilities for truck hydraulic brakes would be a requirement in the near future. Bendix, as a major independent supplier of power brake boosters, had more than a casual interest in this trend appearing over the horizon. As the result of discussions with customers and our internal analysis of various power booster systems, hydraulics, in the form of the Bendix Hydro-Boost system with an integral electric motor pump backup, was settled upon as one major approach to best serve the industry.

An initial report presenting order of magnitude data only. Owning, operating, and maintaining fleets of line-haul and pickup and delivery units has its own peculiar problems. This paper considers questions such as what manufacture of vehicle should be selected, reliability of the product, whether or not to perform maintenance, etc. Specifically covered is the possible problem area of drivetrains; a preliminary standard operating system developed by the American Trucking Assn., Inc. is given.

This paper discusses the history, theory, operation, and refinements of one of the oldest limited-slip vehicle axle and tandem interaxle differentials that has remained in continuous production. The design uses a cam and wedge principle, but is a true differential in the manner of a conventional geared unit. Its unique drive principle provides frictional bias in a ratio between 2-3:1 to increase vehicle drawbar pull on split-coefficient surfaces.

The approach taken in the design, development, and application of an Oshkosh powershift transmission for on/off-highway truck use is described. The Oshkosh transmission design has a building block concept, and in its basic form consists of a two-speed splitter auxiliary attached to the four-speed main drop box to provide a transmission with eight forward speeds and two reverse speeds. The two-speed splitter auxiliary may be omitted to provide a transmission with four forward speeds and a single reverse speed. The eight-speed transmission will be capable of use with high speed, low torque engines, or with low speed, high torque engines. This is accomplished by changing the input ratio gears. The overall ratio of the transmissions may also be changed to match tire size and/or axle ratios. The ratio changes for engine speed-torque and/or overall ratio may be made without affecting the transmission range or physical configurations.

The operation and application of the NoSPIN and Tandem-Lock differentials to power transmissions is described. The three types of NoSPIN-standard, silent, and silent-overrunning-and two of Tandem-Lock-conventional NoSPIN and inside-out design-are described, and the positive and negative features of each are considered. The paper points out the early design deficiencies and the corrective action taken to overcome them. The application guidelines of the NoSPIN and Tandem-Lock differentials are also covered so that proper application of the differentials can be carried out.

This paper describes a shiftable controlled traction differential developed for both on and off highway heavy-duty truck application. The differential can provide greater limited slip action when engaged for adverse driving conditions than current designs and yet not have the undesirable aspects normally associated with limited slip differentials. There is also a unique lubrication system that extends the life of the unit.

The types of noise problems confronting the urban dweller and the legislation dealing with such noises are discussed in this paper. Of prime consideration are vehicular transportation, mass transportation, and railroad noise. Current noise regulations in Chicago are reviewed and the needs of future legislation explored.

Various methods have been used to restrict differential action in drive axles to prevent loss of traction. Although these methods differ in principle, they exhibit similar characteristics. Based on tractive effort performance, most devices can be categorized into one of four basic classifications. This paper defines these classes and compares them to requirements needed for the “ideal” differential.

One result of the recent increase in product liability litigation has been the involvement of engineers in the legal environment. This involvement has been developed through changing theories of liability and increasing sophistication of engineered products. This paper illustrates typical involvement of an engineer in products liability litigation and emphasizes the differences between practicing engineering in a technical environment and in a nontechnical, legal environment. A brief historical discussion of the breach of express warranty, breach of implied warranty, and strict liability theories of products liability is also presented.

Two new 4 X 4 drivetrain systems have been developed for highway tractors that are used to pull multiple trailer combinations. The first one is a 4 X 2 that automatically becomes a 4 X 4 when conditions exist that require 4 X 4 operation. The second one is a full-time 4 X 4 that proportions the drive torque 36% to the front axle and 64% to the rear axle. A unique front driving steering axle has also been developed that permits a 4 X 4 system to be installed in a standard 4 X 2 truck. There is no need to relocate any major components to make space available for a front driving steering axle.

A program was undertaken to determine which retrofit methods are currently feasible for used cars, considering emission reduction effectiveness, cost, effects on vehicle performance, facilities, and labor skill required for retrofit installation, maintenance, and inspection. An extensive search was made for all sources of information on retrofit methods, developers, and producers. Eleven representative retrofit devices were actually tested in this project. A fleet of 20 used vehicles without factory installed exhaust control systems was used for testing the performance of the retrofit devices. The vehicles were tested first without a retrofit device to obtain a reference baseline, and then with retrofit device installed. Emission tests were conducted by the 1972 CVS Federal Test Procedure. Fuel consumption was also measured during the CVS test. Drivability tests were conducted by an Automobile Manufacturers Association procedure.