The Lestran Orbital IVT. Infinitely Variable Transmission (IVT) Using Oscillating Torque

Transcription

1 The Lestran Orbital IVT Infinitely Variable Transmission (IVT) Using Oscillating Torque Lestran L.L.C. Lestran 3104 Riverwood Drive Fort Worth, Texas Tel: Abstract The patented Lestran L.L.C. Orbital IVT is a novel automotive transmission design that harnesses the power from the centrifugal force of rotating eccentric masses to create the first Infinitely Variable Transmission (IVT) capable of scaling to large vehicle sizes. The unique design combines the high mechanical efficiency of fixed gear ratio transmissions with the high engine efficiency obtained using a Continuously Variable Transmission (CVT) in a lightweight, rugged, and high-torque package. The simple, high-efficiency design of the Lestran Orbital IVT allows the components to be sized for greater endurance and higher power while remaining smaller than competing designs. The high mechanical efficiency of the Orbital IVT eliminates hydraulic fluids and costly lubrication and cooling methods resulting in a dramatically higher maintainability and lower operating cost. The small number of parts and the straightforward parts design drive reduced manufacturing costs in both material and labor and increase reliability. The high efficiency design allows the Orbital IVT to support high load, large vehicle applications previously not supported by existing CVT designs. The Orbital IVT can scale to support nearly any size application such as Heavy Trucks, Main Battle Tanks or Earth Movers. This paper describes the Orbital IVT design, key benefits, development activities to date, and discusses areas of needed future research. Lestran L.L.C.

2 Table of Contents Abstract... i Table of Contents... ii 1.0 Executive Summary Need for Improved Transmissions Current State of the Art Problems with State of the Art The Lestran Orbital IVT Lestran IVT Design Details Advantages Over Other CVTs Key Benefits of the Orbital IVT... 6 The Benefit of Constant Power Output at Vehicle Drive... 6 Higher Efficiency Cooler Running Design... 7 Reduce Overall System Weight... 7 Increase Transmission Power Input Density... 7 Operational Cost Reduction Development Overview Initial Models Mini-Baja / Dyno Testing Belt Connected Masses Inertia Control Engine Braking Future Research and Development Summary Lestran L.L.C. ii

3 1.0 Executive Summary 1.1 Need for Improved Transmissions In a military environment, any improvements in low-end torque and acceleration can significantly improve the vehicle s utility. Troops and equipment get to the target sooner and maneuver more efficiently on scene providing major improvements to the vehicle s tactical capability, decreasing wear on vehicle components, improving reliability, and lowering the need for costly and dangerous field repairs. Improvements in Mean- Time-Between-Failure (MTBF) and Mean-Time-To-Repair (MTTR) have dramatic impacts on the ability to keep the vehicle and its users engaged and effective. While engine technology has steadily progressed over the last 100 years, significant improvements in vehicle transmission technology have been incremental at best. While many incremental improvements have occurred, the vast majority of military and civilian vehicles still utilize either traditional manual shift transmissions or incremental improvements over automatic transmissions such as additional gears or shift on the fly. As a result, the traditional manual transmission was utilized heavily in most vehicles since its invention with very little subsequent innovation. In many parts of the world automatic transmissions have become popular for their ability to free the vehicle operator from the task of proper gear selection, but they did not provide improvements in fuel economy. Automatic transmissions provide convenience at the expense of efficiency and dependability. In the last decade broad adoption of Continuously Variable Transmissions (CVTs) has begun. Figure 1 shows the three classes of transmission. The fixed gear ratio transmission provides a fixed number of forward and reverse gears. A continuously variable transmission provides an infinite number of forward gears and a single reverse gear, but does not provide gearing near zero output speed, and hence still needs a torque converter. The Orbital IVT provides an infinite number of forward and reverse gears with significant torque transfer near zero velocity eliminating the need for a separate torque converter. Fig. 1 Transmission Types The continuously variable transmission provides the convenience and performance of an automatic transmission without sacrificing engine efficiency. The CVT achieves higher system efficiency by allowing the engine to operate or near the peak engine efficiency at all times. This increased efficiency is a major advancement in automatic transmission technology. Lestran L.L.C. 1

4 However, typical CVT designs utilized today are incremental improvements on the torroidal drive which have complex drive components with tight machining tolerances. As a result these traditional CVTs are expensive to produce and have a historically higher failure rate than the manual or automatic transmissions that they replace. Current generation CVTs also have inherent power-handling limitations that make them impractical for use in all but the lightest-duty applications. These shortcomings are overcome by the unique design of the Lestran Orbital IVT. The Orbital IVT combines the automatic shifting advantages of automatic transmissions with greater efficiency and dependability than even manual transmission systems can provide. This white paper will describe in more detail the operation and limitations of traditional gear-ratio transmissions and state-ofthe-art Traditional CVT transmissions, followed by an explanation of how the Lestran Orbital IVT solves the problems of both, while providing higher levels of efficiency and dependability than either. 1.2 Current State of the Art For large commercial and military vehicles the current state of the art is still manual transmissions with many fixed speeds. The current state-of-the-art in automatic transmissions comprises two distinct areas. First, automatic fixed gear ratio transmissions are being offered with more gears and over-drive along with shift-on-the-fly control. While these changes improve the driving experience, they do not dramatically improve the overall vehicle performance. In fact, systems such as shift-on-the-fly can actually decrease vehicle efficiency; therefore, we will not discuss these transmissions in detail here. Second, much effort is being expended on the development of CVT systems. In terms of advanced design and efficiency, the CVT is the current leader. The first operational CVT, which was developed circa 1890, included a disk-wheel combination where the position of the drive wheel relative to the center of the driven wheel determined the drive ratio. Many CVT designs have been demonstrated since that time. All major automobile manufacturers offer at least one vehicle with a CVT, most often for low-horsepower and high fuel efficiency vehicles. Continued increases in fleet-wide fuel efficiency standards will force this trend to continue. The current class of CVTs being offered in production vehicles all rely on either some form of the torroidal or chain-drive CVTs. These CVTs have a less-favorable power-to-weight ratio and many components with tight machine tolerances that drive the manufacturing cost significantly higher than competing fixed gear ratio designs. However, due to the significant operational benefit, these higher costs are being accepted to gain the system efficiency benefit they provide. These CVT designs have additional problems related to service life and mechanical efficiency. The torroidal CVTs are made up of discs and rollers that transmit power between the discs, while the chain-drive CVTs are made up of two V-belt pulleys that are split perpendicular to their axes of rotation, with a V-belt chain running between them. 1.3 Problems with State of the Art Both fixed gear ratio and CVT transmissions suffer from major shortcomings that are corrected by the Lestran Orbital IVT. Major shortcomings of automatic and manual fixed gear ratio transmissions are: High Complexity - More than any other design, both automatic and manual fixed gear ratio systems depend on large numbers of components to do their job. This complexity decreases efficiency and increases the numbers of parts that suffer wear and lead to system failure. The large number of gears increases component manufacturing and system assembly costs. Lestran L.L.C. 2

5 High Heat Generation - Fixed gear ratio transmissions lose large amounts of energy to heat, which must then be dissipated by the transmission and other critical vehicle systems. The high heat generation creates a need for specialized transmission fluid and transmission cooling systems, further increasing the cost of the total system. Low Engine Efficiency Fixed gear ratio transmissions tie output speed directly to engine speed for a limited number of speed-ratios. As a result, engine speed is outside of the optimal range for large amounts of time under normal operating conditions. When a change in vehicle speed is required, both the engine speed and the transmission gear ratio must be varied. This causes the engine to operate either above or below its optimal speed a majority of the time. This phenomenon is exaggerated in city driving, which is the major contributor to the large disparity between city and highway fuel economy in most vehicles. High-Loss Torque Converter - In order to generate the large amounts of torque needed to accelerate a vehicle s mass from a standstill, a torque converter with a hydraulic fluid coupling is used to increase the torque transmitted from the engine to the transmission. The torque converter consumes large amounts of energy to produce the required torque. The major shortcomings of traditional CVT transmissions are: High Complexity / High Cost - As with automatic fixed gear ratio transmissions, CVTs are highly complex. This complexity increases component and assembly costs, decreases efficiency, and increases the number of parts that suffer wear and lead to system failure. Low Power Capacity - Although CVTs increase efficiency by keeping the engine at its optimum speed, inherent constraints on most existing CVT designs decrease the maximum torque that can be produced. Although many small advances have been made in this area of CVT design, real progress is minimal due to these inherent constraints to their power-to-weight ratio. Limited Service Life - Most CVT designs rely on drive components with high failure rates and unusual fluids and components that are expensive to manufacture. This creates increased manufacturing and maintenance costs, and limited service life. Lestran L.L.C. 3

6 2.0 The Lestran Orbital IVT Lestran s patented Orbital IVT (U.S. Patents 6,044,718 and 6,062,096) is a new class of continuously variable transmission (CVT). The Lestran Orbital IVT adds a new dimension to transmission technology by supplying exceptionally high torque, high power efficiency and compact design to meet even the highest performance demands of military, passenger and commercial vehicles. Additionally, the Orbital IVT offers even greater power and efficiency and a nearly unlimited load capacity. The compact design and simple components reduce manufacturing and maintenance costs. The Lestran Orbital IVT harnesses the power from the centrifugal force of rotating eccentric masses to create the first Infinitely Variable Transmission capable of scaling to large vehicle sizes. This novel IVT design combines the high mechanical efficiency of fixed gear ratio transmissions with the high engine efficiency obtained using a CVT in a simple, lightweight, rugged, and high-torque package. The simple, high-efficiency design of the Lestran Orbital IVT allows the components to be sized for greater endurance and higher power while remaining smaller and lighter than competing designs. The high mechanical efficiency of the Orbital IVT eliminates hydraulic fluids and costly lubrication and cooling methods resulting in a dramatically higher maintainability and lower operating cost. 2.1 Lestran IVT Design Details Unlike conventional fixed-gear-ratio or CVT transmissions, the Orbital IVT does not rely on direct coupling of gears or limited slip components to produce power. The Orbital IVT harnesses the power from the centrifugal force of rotating eccentric masses to create an oscillating torque. Multiple one-way clutches rectify the oscillating torque output to convert the power into a unidirectional torque. Infinitely variable torque, from zero torque to the full capability of torque output, can be produced with no clutching or torque conversion required at the input. This design produces a true IVT, with geared neutral and fullspeed reverse. Infinitely variable control of the amplitude of the torque results from the change in the center of gravity of the rotating masses. The following section describes the high level basic Orbital IVT design details. For full design details contact Lestran L.L.C. or see the white paper Orbital IVT Design Details. The IVT consists of three component groups; (1) the input assembly, (2) the arm assembly, and (3) the output assembly. The input assembly consists of two sets of linkages, sprockets, and timing belts. The linkages are connected to the rotational power source and pull the sprockets in a circular path around the arm assembly. These sprockets produce large centrifugal loads which generate an oscillating torque. The timing belts are used to transfer the centrifugal loads to the arm assembly. The Fig. 2 Lestran IVT Cutaway centrifugal loads are equally distributed on both sides of the timing belts. The arm assembly is a shaft with eccentrically mounted sprockets and is the structural interface between the input and output assemblies. The moment arm for the oscillating torque is the distance from the center of the arm assembly shaft to the center of the eccentrically mounted sprockets. Lestran L.L.C. 4

7 The output assembly consists primarily of the casing, alignment bearings and two one-way clutches which convert the oscillating torque into a unidirectional torque. The two one-way clutches constrain the rotation of the arm assembly in opposite directions. The first one-way clutch is coupled between the arm assembly shaft and casing to limit the motion of the arm assembly and the second one-way clutch is coupled between the arm assembly shaft and an output shaft to transfer the torque to the output shaft. The torque amplitude is controlled by adjusting the phase angle between the two sets of linkages, sprockets, and timing belts of the arm assembly. These two sets of linkages, sprockets and timing belts are known as the forward and aft drive units. Maximum output torque occurs when the drive units are in phase. Intermediate torque for phase angles between 0 and 180 degrees. Zero output torque occurs when the drive units are out of phase by 180 degrees. The IVT shifts between forward and reverse by changing the direction of the action of the two one-way clutches. The IVT uses two special one-way clutches that has indexing rates up to 100 Hz, torque capacity that is five times greater than a sprag clutch, and the direction of the indexing action can be switched between clockwise and counter clockwise. 2.2 Advantages Over Other CVTs Unlike conventional gear-drive transmissions or existing CVTs, the Lestran Orbital IVT controls the output torque as opposed to the output speed ratio. Infinitely variable torque, from zero torque to the full capability of torque output, can be produced with no clutching or torque conversion required at the input. The power from the centrifugal forces of eccentric rotating masses is harnessed to create an oscillating torque. One-way clutches convert the oscillating torque to a unidirectional torque. Variable control of the amplitude of the torque results from the change in the center of gravity of the rotating masses. This unique design eliminates all of the high friction components of current industry standard transmission designs promising a mechanical efficiency far exceeding current fielded systems. The high efficiency results in smaller and lighter packaging, higher output, and increased reliability. A major design advantage of the Orbital IVT is the mechanical simplicity of the transmission components, resulting in significantly decreased manufacturing costs. While fabrication of the many gears for traditional transmissions requires advanced machinery, the Orbital IVT components can be manufactured using the most basic machining techniques, significantly reducing manufacturing costs. The above features allow the Orbital IVT to overcome all of the major shortcomings of both existing fixed gear ratio and CVT transmissions. Hence, the Orbital IVT has several major benefits. First; the unique torque transfer design allows the transmission to provide a constant power output over a much broader engine RPM range than any previous fielded design, second; the lightweight, high-torque, design increases the transmission power density while reducing weight, third; the high-efficiency low-cost design improves the thermal performance and eliminates the need for hydraulic transmission fluid leading to a substantial Operational Savings and Cost Reduction. These objectives are critical to obtaining new twentyfirst century advanced transmissions that will make a contribution to the demands for lighter weight and improved mobility to increase vehicle performance and capability. The Orbital IVT has the potential to provide major improvement in transmission technology. These improvements can be applied to virtually any automotive or military vehicle application. Lestran L.L.C. 5

8 2.3 Key Benefits of the Orbital IVT The Benefit of Constant Power Output at Vehicle Drive One of the key operational benefits of the Orbital IVT is constant output power at the vehicle drive. Since the transmission continues to deliver power during changes in torque output, the dead-time between gear shifts is completely eliminated. This characteristic contributes directly to improved acceleration, and handling. In a rough terrain environment where the vehicle drive must match changing terrain conditions, the constant output power improves traction. For the Orbital IVT, constant power is maintained by adjusting the phase angle of the Orbital IVT rotatable masses during the acceleration. As an example, the high acceleration time of the M1A2 Abrams Main Battle Tank from 0 to 20 miles per hour (mph) of 7.2 seconds is an excellent example of the importance of constant power output at vehicle tracks or wheels throughout the entire vehicle speed range. If the maximum power from the vehicle s engine (1500 hp AGT-1500 Turbine Engine) could be directly transferred into kinetic energy the acceleration time would be 2.2 seconds (ratio of vehicle kinetic energy and vehicle engine maximum power). The constant power output characteristics of the Lestran IVT could reduce the acceleration time of the M1A2 from 7.2 to less than 3.0 seconds. Similarly with the 275 hp Detroit Diesel 6V53T in the M113A3 Armored Personnel Carrier, the acceleration time from 0 to 20 mph can be reduced from 7.8 to under 3.0 seconds and with a 6.5L V-8 naturally aspirated diesel engine in the HMMWV, the acceleration time from 0 to 50 can be reduced from 26.1 to under 13.0 seconds. The predicted acceleration times for the M1A2, M113A3 and HMMWV with an Orbital IVT and current engine installed are shown in Table 1. The theoretical best acceleration times are the ratio of vehicle kinetic energy and maximum engine power neglecting any losses such as aerodynamic drag, traction losses, and rolling resistance. The increase in acceleration times is due to the maximum power of the engines transferred to the tracks or wheels as illustrated in Figure 3. Table 1 Predicted Acceleration Times for M1A2, M113A3, and HMMWV Item Symbol M1A2 M113A3 HMMWV units Vehicle Mass m tons lb-sec 2 /ft Vehicle Velocity v mph ft/sec Vehicle Kinetic Energy KE = ½ m v hp-sec Engine Power P hp Theoretical Best Acceleration Time KE/P 2.2* 2.5* 9.2** Sec Current Acceleration 7.2* 7.8* 26.1** Sec Predicted Acceleration Time with Orbital IVT < 3.0* < 3.0* < 13.0** Sec * Acceleration time 0-20 mph ** Acceleration time 0-50 mph Lestran L.L.C. 6

9 Fig. 3 Orbital IVT Power Curves for Selected Military Vehicles Higher Efficiency Cooler Running Design The Orbital IVT has few energy dissipating components which provide a high mechanical efficiency exceeding 98% for most operational conditions. This high efficiency even during periods of high torque output allows the Orbital IVT to run without special cooling or lubricating components such as hydraulic transmission fluid or transmission coolers. The design of the Orbital IVT allows the transmission to operate even in the highest torque environments with only standard engine oil as a lubricant. Torque converters are a hydraulic device consisting of a pump runner and turbine in a close-coupled package to provide torque multiplication. In the process of torque multiplication torque converters have high power losses. The Lestran IVT s high torque characteristics eliminate the need for torque converters. Reduce Overall System Weight The Orbital IVT has fewer than 30 primary components, enabling it to be sized for higher power, higher torque, increased service life and reduction in overall system weight. The weight of the Orbital IVT would be less than two thirds of the weight of a traditional transmission. This is accomplished with all of the components made from common metals such as steel and aluminum. Increase Transmission Power Input Density The Lestran IVT is a new class of transmission that provides infinitely variable torque control. The dynamic characteristics and compact design provide higher transmission power input density than traditional transmissions. The increased transmission power input density enables nearly any existing application to be retrofitted with the Lestran IVT within the same space occupied by the current transmission. Operational Cost Reduction An Operational Cost Reduction is achieved through reduced maintenance and use of a common lubricant for the engine and transmission. Maintenance is reduced by a simplified design that enables the components to be sized for an increased service life while still reducing the system weight below existing systems. Since lubrication fluid is only needed for the bearings and the one--way clutches in the transmission, the same lubricants used in the vehicle s engine are appropriate for use in the IVT. Improved transmission Mean- Time-Between-Failure (MTBF) and elimination of the logistics effort required to manage the special hydraulic transmission fluid reduces overall system costs. Lestran L.L.C. 7

10 3.0 Development Overview 3.1 Initial Models The concepts behind the Orbital IVT have been refined through the development of a number of prototypes and analytical models. Numerous desktop model and small vehicle prototypes have been constructed to validate and demonstrate the basic concepts and assist in the ongoing development. Lestran continues to refine the Orbital IVT design and has ongoing patent applications on the latest developments. Early prototypes proved the basic torque transfer capabilities both in desktop and small vehicle designs. Figures 3 and 4 show early models installed in a go-kart to demonstrate the Orbital IVT torque transfer. The transmissions supplied smooth acceleration and high torque. By changing only the transmission, a dramatic improvement in low-end torque was observed. In early Lestran IVT prototypes the rotating masses were connected to the shafts using bearings as can be seen in Figure 4 between the inner section of the rotating masses and the main shaft. The forces on the rotating mass bearings were the limiting design feature that determined the transmissions ultimate power capacity. See section 3.2 for later belt connected prototype designs. The desktop prototype shown in Figure 5 includes variable mass angle control. This model demonstrated true IVT output characteristics with control of output torque from zero output with the masses out of phase and full torque output with the masses in phase. Fig. 3 Early Go-Kart Model Fig. 4 Improved Go-Kart Model Fig. 5 Desktop Model with Variable Mass Angle Control Lestran L.L.C. 8

11 3.2 Mini-Baja / Dyno Testing A mini-baja all-terrain vehicle (ATV) developed by a student engineering team at Dalhousie University based on the Lestran Orbital IVT (Figs. 6, 7, and 8) showcased the compact design and provided dynamometer data to correlate the analytical models with the physical characteristics of the assembled transmission. Figure 6 shows the assembled transmission in the casing. Figure 7 shows the transmission installed in the mini-baja vehicle. The student team utilized an existing vehicle and engine design and replaced the existing transmission with a transmission using the Orbital IVT concept. Prior to installation of the Orbital IVT prototype, the mini-baja vehicle could not climb stairs. Without changing any engine, chassis, or other drive train components other than the transmission, the low-end torque of the vehicle was increased substantially such that the vehicle could stop on the stairs and accelerate up the stairs from a standing start. At the same time, the top speed of the vehicle was also increased. Figure 8 shows the vehicle approaching and climbing stairs. In addition to the in-vehicle testing, the student team tested the transmission on the dynamometer which validated the analytical models. Fig. 6 ATV Model (Assembled) Fig. 7 ATV Model (Installed) Fig. 8 ATV Climbing Stairs Lestran L.L.C. 9

12 3.3 Belt Connected Masses In early Lestran IVT prototypes the rotating masses were connected to the main shaft with bearings. While this design was simple to construct and served to demonstrate the key concepts in early phases, it was known that the bearings would not scale to higher load cases. Recent development activities have concentrated on a design which eliminates the bearings on the rotating mass shaft by using timing belts or timing chains to hold the centrifugal load of the rotating masses. A working desktop prototype of the belt connected design has been completed and is shown in Figure 9. Followon patents for the belt connected design have been submitted and are in final stages of patent prosecution. In the belt-connected system, the connection to the main shaft is made using sprockets and the rotating masses themselves are also sprockets. The belt-constrained design eliminates the load carrying bearings and significantly Fig. 9 Belt Constrained Prototype increases the overall load carrying capacity of the Lestran IVT system. The initial desktop model was constructed from off-the-shelf timing belt components that provided proof-of-concept of the belt-connected masses concept. The initial model provided smooth operation during initial testing. 3.4 Inertia Control Early desktop prototypes utilized change of phase between multiple groups of rotatable masses to control the torque output of the system. These designs added both mechanical complexity and length to the IVT. New design concepts have been developed that utilize direct control of inertia within the system to achieve torque output control. The new designs are mechanically simpler than the previous designs as well as smaller and lighter. Details of the inertia control systems are currently held as trade secret. 3.5 Engine Braking Larger vehicle applications require engine braking to assist the friction brake systems. Early design concepts for the Lestran IVT did not include engine braking capability. Refinements to the design have been completed which have added the capability to provide engine braking in all versions of the Lestran IVT. Lestran L.L.C. 10

13 4.0 Future Research and Development Prototyping activity to date has continued to show that the Lestran IVT concept is technically feasible and provided initial answers to key questions, most importantly the ability to scale to higher output levels. Additional research and development is needed to refine the system design as well as develop detailed designs for target vehicles to show that the required output power can be achieved within the design constraints of specific vehicles. Additional funding is needed to accelerate these next development steps. Specific next steps would vary depending on the target vehicle, but should include the following: Additional Prototype Testing. Prototype activities to date have been designed to provide proof-of-concept. Prototypes have been installed in desktop fixtures or very small vehicles and operated at low speeds to provide initial assessments on the efficacy of the design. Additional baseline testing on larger proof-ofconcept prototypes should be conducted to provide measurable outputs and validate system design parameters. Initial load testing can be conducted on the desktop or small vehicle models to provide measurement data to assist in validation of design parameters and software models. Larger prototypes should be constructed to demonstrate advantages of the concept for high-torque and high-power applications. Validation of Software Models. Lestran has developed models to predict the output power for various sizes of transmission. The models should be validated and refined through comparison of outputs measurements for specific designs against model predictions for those same designs. Successive Rapid Prototyping. The relatively simple nature of the design compared to traditional transmissions and early CVTs enables the possibility of quick turn-around successive rapid prototyping at relatively low cost. Successive rapid prototyping allows measurements to be taken while slightly varying design parameters model-to-model to provide further insight into the design trade-offs. A variety of proposed designs exist for key system components that can each be tested to achieve the overall best design. This activity allows for quick optimization of the design of key components prior to installation in vehicle systems. Dynamometer Testing. Dynamometer testing will demonstrate the performance of the system in a controlled environment. Load testing should be conducted on an engine mounted or vehicle mounted dynamometer to enable precision measurements of the input-output characteristics of the design. Dynamometer testing should include ramp-up testing at increasing loads while monitoring the system for signs of load or friction induced stresses. Scaled Up Designs. Load and dynamometer testing should be conducted on various scaled up design prototypes to collect measurement data that can be correlated to changes in size. Improved Belt Designs. Initial belt-connected designs utilized off-the-shelf and readily available timing belts to carry the rotating masses. Initial successive rapid prototyping activities would also utilize off-theshelf belts to vary the design parameters as quickly as possible without requiring custom belt development. Ultimate IVT power density is largely a function of belt load carrying capacity both in distortion and breaking strength. While many off-the-shelf belt options exist, their designs have been optimized for tooth forces from turning sprockets. The primary belt loads in the IVT are pulling loads rather than turning loads. While these changes are not considered high-risk or long-lead, the development will be limited by belt strength and should be addressed early. Lestran will need to work with the belt manufacturers to develop increased strength belts resulting in smaller and higher load carrying transmission. Increases in belt strength will directly contribute to smaller diameter and shorter IVTs with higher load carrying capacity providing further options for incorporation into a wider variety of vehicles. Lestran L.L.C. 11

14 Control System Development. While the control system is not considered a high-risk item, control system development needs to keep pace with the mechanical development of the primary IVT components. A candidate control system design should be constructed and tested on one or more of the prototype transmissions. Installation in Basic Vehicle. Installation of a prototype IVT into a larger vehicle should be completed to evaluate the basic driving characteristics of the design. Vehicle Specific Designs. After load measurements and testing, additional vehicle specific designs can be constructed to evaluate the driving characteristics of the IVT in the target vehicles. Target Vehicle Testing. After target vehicle designs have been initially tested in the laboratory, the system can be scaled to any target vehicle size. Reliability Testing. Simulated load testing should be conducted over long periods of time to assess the longterm performance of the system and provide information needed to refine the system design for maximum lifetime. 5.0 Summary The Lestran Orbital IVT is a novel transmission design with many benefits over existing fixed gear ratio transmissions and even the newest continuously variable transmissions. The Orbital IVT design is simple and inexpensive to manufacture, and highly reliable, resulting in lower manufacturing costs and dramatically lower total cost of ownership. Key benefits include; (1) lower manufacturing costs, (2) lower operating costs, (3) constant power at the vehicle drive over a wide range of torque and speed settings, and (4) increased power density for smaller and lighter weight packaging. Further, the Orbital IVT is the first Infinitely Variable Transmission that can provide the torque required for large commercial and large military vehicle applications. Various models and prototypes have shown that the transmission conceptual design does translate into working systems. Areas for future research and development have been presented. For more information on the Orbital IVT contact Lestran L.L.C. at terry.lester@lestranivt.com or Lestran L.L.C. 12