Browse Topic: Hydrostatic transmissions

Items (233)

Necessity of damper for Hydrostatic Transmission (HST) Tractors

2021-26-027809/22/2021

In a modern world, the tractor customer demands are increasing for more comfortable, new technology, fuel efficient and quieter vehicle. The customer’s expectation for NVH refinement often challenges the limitations for tractor designs. For smaller tractors Hydrostatic Transmission (HST) is need due to higher demand for fuel efficiency, lightweight powertrain, and the operation will become easy in the field. With the Hydrostatic Transmission (HST) tractor without damper, there is a technical challenge like withstanding of the sudden impacts from the implements which are connected to PTO during field operations. The NVH behavior in driveline is critical phenomena which can cause the discomfort to end users and structural failure of driveline parts. During gear engagement due to sudden variation in torque the driveline parts are tends to clash each other because of lashes which will create high level of angular acceleration and noise. Practical measurement study has been done to identify

Rajendran, Ashok Kumar, Bagadekar, Vijaykumar, Alavilli, Satya Pavan

Hydraulic Motor Test Procedures

J746_201911 (Current)11/20/2019

This test code describes tests for determining characteristics of hydraulic positive displacement motors as used on off-road self-propelled work machines as referenced in SAE J1116.

CTTC C1, Hydraulic Systems

Modeling of the Automatic Power Distribution System among the Traction Motors of the Driving Wheels of a Multi-Axle Vehicle

2019-01-091404/02/2019

Dynamics of acceleration, mobility, fuel efficiency of wheeled vehicles are largely determined by the drive circuit to the driving wheels and bridges, as well as devices used in drive link nodes to distribute power among the driving wheels. This is especially important for multi-axle wheeled vehicles. In this paper, the object of the study is a multiaxial wheeled vehicle with an electric transmission consisting of an internal combustion engine with a power of 720 kW, one common generator and twelve traction motors mounted directly on the driving wheels. In connection with the change in load on the driving wheels due to the variability of soil properties, driving conditions (acceleration, braking, uniform motion), terrain topography, it is necessary to provide external regulation of electric machines working in the transmission of the vehicle. The aims of the work are: 1) the study of currents and voltages in traction motors while changing the properties of the ground during the

Kondakov, Sergei, Pavlovskaya, Olga, Aliukov, Sergei, Smirnov, Vladimir

Development of a Compact and High-Performance Torque Converter Based on a New Parameter Sensitivity Mapping

2019-01-130804/02/2019

Automatic transmissions are required to obtain higher efficiency and to reduce their size and weight in order to improve environmental friendliness and fuel economy. Especially in the torque converter development process, there is a need to strengthen the torque multiplication capability to compensate driving force in the non-boost region as a result of recent trends toward engine downsizing. At the same time, there are more rigorous space-saving requirements from the standpoint of ensuring vehicle collision safety. To meet these various requirements, a new torque converter has been developed that provides world-class performance in a minimized torus size. The capacity factor and the torque ratio are the two major parameters of torque converter performance. There are many dimensional parameters concerning the blades and cross-sectional shapes of torus that must be considered in the performance design. It is difficult to optimize these parameters because they involve numerous tradeoffs

Kawashima, Kazunori, Endo, Masatsugu

Automotive Transmission Terminology

J645_201708 (Historical)08/25/2017

The following listed definitions are intended to establish terminology and criteria for describing the various kinds of automotive transmissions. A specific arrangement may be described by a combination of several of these definitions.

Automatic Transmission and Transaxle Committee

Aerospace – System Integration Factors That Affect Hydraulic Pump Life

AIR1922B (Current)02/13/2017

This SAE Aerospace Information Report presents the following factors that affect hydraulic pump life and performance: a The need to supply hydraulic fluid at the correct pressure and quality to the pump inlet port b Considerations for the pump output c Factors to be considered for the pump case drain lines d The mounting of the hydraulic pump e Hydraulic fluid properties, including cleanliness

A-6C4 Power Sources Committee

Integrated Cooling Evaporation System for the Hydraulic Retarder

2015-01-161204/14/2015

The hydraulic retarder is a significant auxiliary braking device [1] for the heavy duty vehicle. Traditionally, cooling circulatory system of the hydraulic retarder was coupled with the engine cooling system [2], and the thermal energy of the transmission medium would be cooled by the engine radiator ultimately. For this scheme, radiator's spare heat removal capacity could be fully utilized whereas the cooling system is very complicated and is hard to maintain. Furthermore, the corresponding of thermal management system lags behind the power change of the retarder. In this research, integrated cooling evaporation system is developed for the hydraulic retarder, which makes the cooling water contact with the transmission medium through the stator wall, so that it can rapidly response to the thermal variation of the retarder, keep the stability of the oil temperature and meanwhile reduce the risk of cooling medium leakage. First of all, transmission medium flow regime in the retarder is

Liu, Wei, Tan, Gangfeng, Li, Jiafan, Li, Xin, Mou, Fuzhao, Ge, Yongqiang

Recent Developments in a Novel Blended Hydraulic Hybrid Transmission

2014-01-239909/30/2014

A novel Blended Hydraulic Hybrid transmission architecture is presented in this paper with benefits over conventional designs. This novel configuration combines elements of a hydrostatic transmission, a parallel hybrid, and a selectively connectable high pressure accumulator using passive and actively controlled logic elements. Losses are reduced compared to existing series hybrid transmissions by enabling the units to operate efficiently at pressures below the current high pressure accumulator's pressure. A selective connection to the high pressure accumulator also allows for higher system precharge which increases regenerative braking torque and energy capture with little determent to system efficiency. Finally operating as a hydrostatic transmission increases transmission stiffness (i.e. driver response) and may improve driver feel in certain situations when compared to a conventional series hybrid transmission. To explore the novel blended hybrid architecture six transmissions were

Sprengel, Michael, Ivantysynova, Monika

Quasi-Continuously-Variable Transmission Provides Hydraulic Regenerative Braking for Passenger Cars, Trucks, and Buses

2014-01-171704/01/2014

A hydro-mechanical transmission is described that approximates the “gearing” performance of a continuously variable transmission and incorporates all functions required for hydraulic regenerative braking. Other characteristics such as efficiency, noise, and responsiveness, match or exceed that of present day conventional automatic transmissions. Performance and physical sizing are shown for passenger vehicle, bus and truck transmissions.

Recognition of Operating States of a Wheel Loader for Diagnostics Purposes

2013-01-240909/24/2013

In this paper, the operating states of a wheel loader were studied for diagnostics purposes using a real time simulation model of an articulated-frame-steered wheel loader. Test drives were carried out to obtain measurement data, which were then analyzed. The measured time series data were analyzed to find the sequences of operating states using two different data sets, namely the variables of hydrostatic transmission and working hydraulics. A time series is defined as a collection of observations made sequentially in time. In our proposed method, the time series data were first segmented to find operating states. One or more segments build up an operating state. A state is defined as a combination of the patterns of the selected variables. The segments were then clustered and classified. The operating states were further analyzed using the quantization error method to detect anomalies. The recognized operating states define the operation of the machine so the analysis can be focused

Krogerus, Tomi, Hyvönen, Mika, Huhtala, Kalevi

Development and Testing of a Hydraulic Hybrid Concept for Off-Highway Vehicles

2013-01-242709/24/2013

The paper illustrates the development of a hydraulic hybrid powertrain concept for off-highway vehicles, which is the result of a three-year program at Dana's advanced technology centers. Engineers have conducted extensive simulations and tests while equipping a demonstration vehicle to determine feasibility, develop advanced features, and quantify benefits of hydraulic hybridization for traction. The system concept and operation as well as its development process are illustrated, focusing the system engineering principles and on the model-based approach to system design, control, and energy analysis. Experimental results are provided.

Serrao, Lorenzo, Ornella, Giulio, Burgio, Gilberto, Cosoli, Ettore

ARP719B (Current)06/17/2013

It is intended that this SAE Aerospace Recommended Practice (ARP) will set down guidelines for the development and test of gas motors to provide a practical and reliable hot gas rotary actuation mechanism. Specific operational and test requirements shall be specified in a detail specification.

A-6C4 Power Sources Committee

Modern and Future Motor Vehicles as Modular-Based Complexes of Mechatronic Systems

2012-01-116304/16/2012

The article presents results of comprehensive theoretical and experimental studies aimed at creation of traction-and-transport vehicles (TTVs) - trucks and tractors of the future, which meet the modern requirements for their active and environmental safety. The concept is based on the original complex mathematical model (CMM), which allows simulating various interaction schemes of all TTV systems, including those accounting for the contact (tribological) interaction of the wheel with the rolling surface. The CMM was used to study the work of all the subsystems of TTVs equipped with electric transmission, all-wheel steering and electro-hydraulic servo system of wheel turning, as well as with the wheel-springing system and the onboard information-and-control system. Besides, the CMM and its individual units were used as simulators for programming the functionality algorithms of all these subsystems and their relationships with each other. Based on theoretical studies, unique experimental

Beloousov, Boris Nikolaevich, Ksenevich, Tatiana

Analysis and Guidelines for Design of Efficient Power-Split Systems

2012-01-030404/16/2012

The article is divided into two parts. The first part is dedicated to the analysis of mechanical systems by means of the matrix method. The power of the matrix method lies in its easy implementation in computer calculations. In this article we will present the program “SunGear.” This program is devoted to calculation of such Power-split systems and complete analysis of mechanical stepped planetary gearboxes. The second part of the article will describe the analysis of Power-split systems. In our study we focus on Power-split systems with mechanical CVT. The analysis will be presented by means of two examples: a) IVT (no shift elements) with the spread from reverse (ratio equals −2) up to the overdrive with a ratio of 0,6. The power is split between CVT (spread 0,25 up to 4) and mechanical gear set. The differential (planetary or bevel gear device with 2 degrees of freedom) is placed on the input or on the output of the mechanism. A set of 24 different compositions of mechanisms which

Achtenova, Gabriela, Budinsky, Tomas

Aerospace - System Integration Factors That Affect Hydraulic Pump Life

AIR1922A (Historical)01/03/2011

This AIR presents the following factors that affect hydraulic pump life and performance: a The need to supply hydraulic fluid at the correct pressure and quality to the pump inlet port b Considerations for the pump output c Factors to be considered for the pump case drain lines d The mounting of the hydraulic pump e Hydraulic fluid properties, including cleanliness

A-6C4 Power Sources Committee

A Power-Split Hybrid Hydraulic Vehicle Transmission Modeling and Comparative Analysis

2010-01-201010/05/2010

Recent innovative drives in hydraulics could introduce very competitive hybrid hydraulic vehicles (HHV). These drives has been considered and analyzed only in the serial HHV architecture. The series-parallel transmission architecture, also called power-split or e-CVT is highlighted as the most popular concept for full (strong) hybrid electric vehicles (HEV). The examples are one-mode power-split in Toyota Prius and two-mode (compound) power-split in GM-Allison EVT. Ambitions to make the hybrid hydraulic power trains better and more efficient would certainly require deeper analysis of more complex power-split (series-parallel) HHV transmission structures and related optimal controls. This paper presents bond graph based mathematical model of kinematics of a one-mode and a two-mode power-split hybrid hydraulic vehicle transmissions which are based on their hybrid electrical counterpart. Such models serve as a basis for the analysis of the steady-state behavior of two representative power

Hydraulic Motor Test Procedures

J746_200906 (Historical)

06/12/2009

This test code describes tests for determining characteristics of hydraulic positive displacement motors as used on construction and industrial machinery as referenced in SAE J1116. These characteristics are to be recorded on data sheets similar to the one shown in Figure 1. Two sets of data sheets are to be submitted: one at 49 °C (120 °F) and one at 82 °C (180 °F).

CTTC C1, Hydraulic Systems

Automotive Transmission Terminology

J645_200903 (Historical)

03/03/2009

The following listed definitions are intended to establish terminology and criteria for describing the various kinds of automotive transmissions. A specific arrangement may be described by a combination of several of these definitions.

Automatic Transmission and Transaxle Committee

Synchronized driving

OFHMAR09_0103/01/2009

Tight linkage between engine and transmission increases efficiency. Electronic controls are extending their reach, managing transmissions to improve performance and fuel economy. This transformation comes as engineers focus on ways to synchronize all functions of a vehicle. Now that microcontrollers are a central part of engine design, they are becoming tightly synchronized with transmissions and hydraulic systems. This holistic approach to vehicle design lets engineers do far more fine tuning than is possible with mechanical transmissions.

The drive toward a hybrid transmission

OFHOCT08_0310/01/2008

In-wheel hydraulic motors, hydraulic transformers, and a common pressure rail with accumulators put new meaning in the word drivetrain. Hybrid-electric vehicles are compromises. The pure mechanical transmission is unparalleled when it comes to cost, weight, and efficiency. On the other hand, gear transmissions and even CVT's lack flexibility regarding energy management, energy transformation, and energy storage. Electric systems are in this respect much more convenient, but the power density and the efficiency are too poor to make a full electric drive feasible. However, Innas believes that if a flexible, nonmechanical transmission principle could be found with the same performance, cost, and efficiency as existing mechanical transmissions, there would be no reason for a hybrid configuration. And, the company claims that it has found it: a full hydrostatic all-wheel-drive system that eliminates the complete mechanical drivetrain between the engine and the wheels. The company refers to

New Generation Hydraulic-Mechanical Transmission with Lock-up Mechanisms and Automatic Start Clutch

2008-32-004009/09/2008

New Generation Advanced Hydraulic-Mechanical Transmission (A-HMT) with the Lock-Up mechanism and the automatic start clutch mechanism was developed. In the lock-up mechanism, an electronic control in conjunction with transmission control was adopted using oil temperature, throttle opening, and input / output rotation ratio as parameter to reduce a rotational energy change of input and output axis caused by the volumetric efficiency of A-HMT. In the automatic start clutch, the load sensing function, damper function, and cooling function by replacing the simple hydraulic mechanism are equipped. By these solutions, the transmission efficiency has enhanced approximately 10% compared with former A-HMT, and excellent starting performance and smooth transmission performance have achieved.

Yoshida, Yoshihiro, Yakigaya, Nobuyuki, Nakamura, Kazuhiko, Takeuchi, Kazuhiro, Nakano, Kenichi, Usukura, Yasutaka

Lean Cr Containing PM Materials for Optimized Cost-Performance

2008-32-007409/09/2008

Cr containing PM steels aid optimization of cost-performance for power transmission components in hydrostatic transmissions. Components such as final drive gears and differential gear sets are typical manufactured from sintered materials containing high levels of alloying elements such as Cu, Ni and Mo. Utilisation of Cr-Mo PM materials presents materials with improved cost - performance ratio via improved materials properties combined with improved dimensional tolerances.

Milligan, David, Howe, Ian, Haberberger, Thomas, Cerini, Richard

ARP719A (Historical)

11/06/2007

It is intended that this SAE Aerospace Recommended Practice (ARP) will set down guidelines for the development and test of gas motors to provide a practical and reliable hot gas rotary actuation mechanism. Specific operational and test requirements shall be specified in a detail specification.

A-6C4 Power Sources Committee

Study of Energetic Characteristics in Power Split Drives for on Highway Trucks and Wheel Loaders

2007-01-419310/30/2007

Continuously variable transmissions (CVT) have been gaining popularity because they decouple the engine of a vehicle from the vehicle wheels, providing seamless shifting in vehicle operation and allowing the engine to operate in a speed range where fuel consumption and emissions are minimized. In particular, the power-split CVT, or power split drive (PSD), combines the variability of a CVT with the high efficiency of a mechanical transmission, providing potential benefits for both on road and off road vehicles. Hybrid PSDs allow further fuel savings by transferring the vehicle's kinetic energy to an energy storage device such as a battery, flywheel, hydraulic accumulator or other means during braking and utilizing the stored energy during the next propulsion cycle. While many power split configurations exist in literature (Miller 2005), this paper focuses on a dual stage input coupled PSD with a flywheel energy storage device. The objective of this research work is to describe the

Kumar, Rajneesh, Ivantysynova, Monika, Williams, Kyle

Efficient Recuperation of Kinetic Energy - Hybrid Versus Hydrostatic Approach

2007-01-415310/30/2007

This paper analyzes different concepts for storage and recuperation of kinetic energy during braking operation in a forklift truck application. The reduction of fuel consumption is one of the challenges for on and off-road vehicles. Starting from a conventional hydrostatic transmission, secondary hydraulic control and a hybrid solution are investigated. Wasting kinetic energy during braking operation of mobile working machines in cyclic applications and converting it into heat energy instead of reusable energy is a very inefficient principle still used in industry. Rising energy costs, enhanced government guidelines and increased environmental awareness require more efficient drive concepts for the next decades. Recuperation of kinetic energy during braking operation provides the opportunity of increasing the efficiency of mobile working machines. Efficient recuperation of kinetic energy requires a proper application and a low-loss system design.

Kohmäscher, Torsten, Murrenhoff, Hubertus

Fendt Vario CVT in Agricultural Tractors

2007-01-420510/30/2007

This presentation shows the concepts and the advantages of the Fendt Vario CVT and the features that have been developed to enhance its use in agricultural tractors. The Fendt Vario transmission has been in production for more than 10 years with more than 60,000 tractors built with this CVT concept (until the first half of 2007, Fendt and OEM). As examples emphasize, the CVT helps to optimize the usable power and the fuel economy - especially when compared to power shift transmissions. The machine productivity is further improved by a variety of features like cruise control or constant engine speed for PTO operation with variable ground speed. Acceleration rates are adjustable and reversing can be accomplished with best operator comfort. Further automation and operation systems make the CVT tractor fit to high-end applications. A macro-instruction system allows the driver to store multiple operations. Other main characteristics of a tractor for professionals are mentioned, e.g. anti

Brenninger, Martin M.

A numerical model for the simulation of Diesel/CVT power split transmission

2007-24-013709/16/2007

This paper presents a steady-state numerical model of a power split hydro-mechanical input-coupled transmission for off-road vehicles. In this kind of transmissions the combustion engine is connected to a planetary and to a hydrostatic unit. Depending on vehicle speed and power request, the power is transmitted either hydrostatically or mechanically, or in both ways. The performance of the Diesel engine has been simulated in a simple manner by means of a look-up table, based on the specific fuel consumption map; a similar approach has been adopted for the efficiency of the hydrostatic units. The code is able to predict the overall efficiency of the powertrain, while highlighting the contributions of the hydrostatic path, of the mechanical path and of the engine. The results show how the code can be used both for locating the optimum operating point, as a function of the specific duty, and for analysing different configurations of the transmission.

Casoli, P., Vacca, A., Berta, G.L., Meleti, S., Vescovini, M.

Analysis of a Hybrid Multi-Mode Hydromechanical Transmission

2007-01-145504/16/2007

A multi-mode hybrid hydromechanical transmission (HMT) with infinite variability is designed to meet the power transmission needs of medium duty on- and off-road vehicles. A hydraulic pump-motor assembly provides output speed and torque variability in an input coupled split power configuration. Dual planetary arrangements with two multiplate clutches allow multi-mode ratio change and combination of power from the mechanical and variable branches of the power path. Hydraulic accumulators offer hydraulic power assist during launch conditions and storage of reclaimed energy during braking events. Transmission kinematic, force and power flow analyses will be developed for the HMT and analyzed for suitability in a bus application. The resulting benefits and areas for improvement will be discussed.

Fussner, Doug, Wendel, Glenn, Wray, Chris

Construction and Tests of Swimming Vehicle with Diesel-Hydraulic Power Transmission Feed, Assigned for Special Operation Forces (SOF)

2007-01-142404/16/2007

Siminski, Przemyslaw, Zienowicz, Zbigniew

Electrically Controlled Fixed-Displacement Pump, Variable-Displacement Motor Hydrostatic Transmission

2006-01-346910/31/2006

Fixed-displacement pump, variable-displacement motor configurations are rarely utilized for hydrostatic transmission designs, but they can achieve several advantages over more traditional systems. Developing a hydraulic drivetrain to accomplish high efficiency at high torque is often difficult because variable-displacement pumps are less efficient at low displacements. However, a system that utilizes modern electro-hydraulic valves and an electrically controlled variable-displacement hydraulic motor is easy to modulate and achieves its peak efficiency at low speeds. During the 2005 ASABE (American Society of Agricultural and Biological Engineers) ¼ Scale Tractor Student Design Competition, one such system was compared to conventional hydrostats and belt driven continuously variable transmissions. The fixed pump, variable motor system proved to be easy to operate. An electronic controller was used to modulate motor displacement to maintain constant engine speed. From data gathered

Holland, Michael A., Harmeyer, Keith, Lumkes, John H.

Comparison of Operational Characteristics in Power Split Continuously Variable Transmissions

2006-01-346810/31/2006

Continuously variable transmissions (CVT) provide seamless shifting in vehicle operation, allowing the engine to operate at a nominal speed range resulting in lower fuel consumption and emissions. However, typical CVTs suffer from either low shaft-to-shaft efficiency or low torque handling capabilities. The power split CVT combines the variability of the CVT with the efficiency of a mechanical transmission, providing potential benefits for both on road and off road vehicles. By modifying the architecture and layout of a power split transmission, the characteristics and maximum speed of the vehicle drive cycle can be altered. This paper will present a comparison between the different architectures of power split transmissions utilizing hydraulic units as the variators, with a focus on efficiency, control effort, and system complexity. Applications based on the characteristics of the specific transmission architectures will be suggested.

Carl, Blake, Ivantysynova, Monika, Williams, Kyle

The Prototype and the Simulation Results of Hydraulic Power Transmission of Teleoperated Skid Steered Mobile Machine

2006-01-347010/31/2006

The goal of the paper is to study the properties of a teleoperated mobile machine by means of simulation model of the system and measurements. In this paper some parts of the prototype of the teleoperated machine and the verification results of simulation model of the mobile machine are introduced. The challenge in teleoperation is to have a smooth and accurate control of the machine, because the operator can not feel any force feedback. The machine is valve controlled and the influence of different types of valves is significant for the control of the machine. In this paper is studied via simulation model different kind of valve solutions such as different spool types and effect of pressure compensator among others. The goal in future is to have a totally autonomous mobile machine and it needs more research and development work. With simulation model of the machine it is possible to test new components and hydraulic solutions for power transmission of the mobile machine. In paper

Vilenius, J., Hyvönen, M., Vuohijoki, A., Karhu, O., Moya, J., Huhtala, K.

New Transmission Technologies on Gear Requirements for Global Powder Metal Industry

2006-01-039604/03/2006

Auto companies are transforming four and five speed to six and seven speed transmissions. Manual transmissions are being converted to dual clutch design and it is anticipated in North America true manual transmissions will be extinct. Continuous variable transmission although making slow inroads is a threat to PM. Hybrid vehicles using battery powered electric motors and fuel cell powered electric motors pose a continuing challenge to PM. This presentation will cover the new technologies and their impact globally on automotive transmission and opportunities for PM.

Narasimhan, Kalathur S., Boreczky, Eric

Hydraulic matters

OFHAPR05_0304/01/2005

There is much potential for gain for everyone if OEMs and suppliers work together early in terms of hydraulic system design. Modern off-highway equipment is some of the most powerful, most productive, most impressive machinery ever built. The key to that success is fluid power. It seems, in fact, that the primary function of equipment is to deliver fluid power to the site so that buckets and blades can do their work. As such, it is imperative that OEMs work closely with fluid-power-component manufacturers, no matter how big the OEM, or how vast its knowledge of fluid power.

Power Split Transmissions Versus Hydrostatic Multiple Motor Concepts - A Comparative Analysis

2004-01-267610/26/2004

The aim of the presented study was to analyze the potentials of two different drive line concepts. The comparison is made for a simple Power Split Drive and a Hydrostatic Two-motor Transmission with a disconnectable hydromotor. The main focus is put on the achievable overall efficiency of both alternatives. The system complexity of the two compared transmissions is very different. The analysis therefore also looks towards this matter and further makes an assessment of the different control requirements.

Krauss, Alexander, Ivantysynova, Monika

Drive Line Control for Off-Road Vehicles Helps to Save Fuel

2004-01-267310/26/2004

A new control concept was developed to minimize the power losses of a hydrostatic drive line for off-road vehicles. The drive line control concept is based on two separate closed loop controls, one for the hydrostatic transmission and another for the combustion engine. The command values for both control loops are calculated under consideration of the characteristic curves of the combustion engine and the losses within the hydrostatic transmission, using an on-line optimization procedure. This paper discusses the benefits of this control concept based on a comparison of typical realistic driving manoeuvres. Objective of the investigations for different output powers is the potential of fuel savings under different operating conditions. A hardware-in-the-loop test rig for the investigated hydrostatic propel drive is used for the experimental validation.

Ossyra, Jean-Claude, Ivantysynova, Monika

Changing demands reshape hydraulic components

OFHAPR02_0104/01/2002

In a world of shrinking margins, fierce competition, and increasing regulations, equipment owners want nothing less than stellar performance from their equipment. New technology helps off-highway OEMs respond to equipment-owner demands for faster, cheaper, and more reliable vehicles. So do new business practices: most OEMs are compelling suppliers to re-examine their technologies and practices. “OEMs are trying a purchase strategy much like that used by the automotive people where you have Tier 1 and Tier 2 suppliers,” said Joe Maher, Marketing Manager, Poclain Hydraulics. “The idea is that if they can consolidate their suppliers, those suppliers (will) have more volume, which should generate some cost reduction. And because you're dealing with fewer suppliers, you've saved some administration cost, as well.”

Concepts and Development Trends for Efficiency Improvement of Hydrostatics in Mobile Applications

2002-01-142203/19/2002

In mobile vehicles such as earth moving machines, agriculture machines, forest machines, industrial and mining lifters there is a demand for sophisticated performance. Since the requirements on productivity are very high for mobile machinery, high output capacity combined with high overall efficiency over a wide velocity range is therefore of great importance. A traditional solution for drive train in mobile machinery is to use a hydrodynamic transmission (torque converter) in series with a multi-speed shiftable gearbox. For heavy machines, engine power above 150 kW, torque converters have been used exclusively until a few years ago. However, the development of hydrostatic drive concepts and microprocessor control have made it possible to be competitive with converter drives. Joining pumps, motors and mechanical gears in smart concepts, so called power split transmissions, has make it possible to keep prescribed output power and velocity range without the need of sophisticated power

Rydberg, Karl-Erik

New Method of Numerical Calculation of Losses and Efficiencies in Hydrostatic Power Transmissions

2002-01-141803/19/2002

The present paper describes a newly developed method of computing the losses and efficiencies of hydrostatic power converters. Unlike previous methods this approach is not based on a physical/technical analysis of a single hydraulic pump or motor type. Instead, it employs purely mathematical methods based on measurement data to provide a universally applicable method for computing the power and efficiency behavior of hydrostatic machinery of any design. The accuracy of the method is confirmed by a comparison of measured and calculated performance and efficiency data.

Food-Grade Fire-Resistant Water Glycol Hydraulic Fluids

2002-01-150403/19/2002

Fire is a serious hazard in many industrial applications requiring the use of approved fire-resistant hydraulic fluids. A subgroup of these applications are facilities for the processing of food which in addition require hydraulic fluids and other lubricants used in these facilities to adhere to specifications set down by the United States Food and Drug Administration (FDA) and enforced by the Food Safety Inspection Service (FSIS) branch of the U.S. Department of Agriculture (USDA). The objective of this paper is to provide an overview of the current requirements in the United States for food-grade fire-resistant hydraulic fluids. Water glycol type hydraulic fluids; currently the only commercial food-grade fire resistant hydraulic fluids available, are compared in properties and performance to standard water glycol hydraulic fluids used in steel making and die casting facilities.

Sherman, J. V., Totten, G. E.

The Method of Great Efficiency Improvement in Continuously Variable Integrated Hydrostatic Transmissions

2002-01-142003/19/2002

In this paper a simple technical solution is presented. This solution allows a significant reduction of a wear of parts in an integrated hydrostatic transmission as well as a great efficiency improvement. This solution is suitable for all types of integrated hydrostatic transmissions and it is easy in application.

Stroganov, Alexander, Drouzhinin, Alexander, Volkov, Yuriy, Zimnikov, Alexander

Development of Single Stage Input Coupled Split Power Transmission Arrangements and their Characteristics

2002-01-129403/04/2002

In recent years there has been an increased interest in the continuously variable split power transmissions as these drive units are capable of vehicle launches and directional changes without using clutches. These tasks are accomplished by appropriately splitting power between the fixed mechanical and variable ratio branches. The power is recombined at the transmission output. A properly designed split power transmission arrangement will improve vehicular agility and reduce variator size. This paper provides characteristics of six single stage input coupled continuously variable toroidal split power transmission arrangements. Mathematical equations are derived for speed, torque and power. A computer program that utilizes the capabilities of Matlab is developed. The program calculates the required fixed and variable branch gear ratios for the predefined variator, planetary and overall transmission ratios. Further, the program produces numerical results and visual plots of relationships

Fussner, Doug, Singh, Yesh

SAE Off-Highway Engineering 2001-10-01

OFHOCT0110/01/2001

More with less through electronic components Off-highway engineers have had to walk a precarious path in recent years by developing engine technologies that offer customers better vehicle performance and regulators lower emissions. The promises and problems of electrohydraulics Engineers acknowledge that electrohydraulics are the way of the future for the off-highway industry, and that the field itself could use a good public-relations campaign to attract more engineering students. Deere goes all out for agriculture To some, it may seem odd that John Deere picked this particular economy to launch over 50 new products, the most in its 164-year history. To others it reeks of confidence. Switching control in hydraulic drives Researchers from Johannes Kepler University believe agricultural machinery can be improved by further advances in motion generation.

SAE Off-Highway Engineering 2001-02-01

OFHFEB0102/01/2001

Hydrostatic transmissions in conventional envelopes Kubota designed a hydrostatic transmission for a compact tractor to improve operator control and increase efficiency and productivity. Design of a hydraulic free-piston engine Dutch companies Noax and Innas have developed an engine in which nearly all combustion energy is directly converted into hydraulic energy. Optimizing tractive performance Canadian researchers correlate analytical predictions and experimental data to determine that the proper matching of front- and rear-tire sizes, aswell as careful control of inflation pressure and normal load of the tires, is necessary to achieve optimum tractive performance of four-wheel-drive tractors. Actively suspending off-road vehicles The University of Texas Center for Electromechanics evaluated a retrofit electromechanical active suspension that s hows promise of improved cross-country mobility for military vehicles.

Hydrostatic transmissions in conventional envelopes

OFHFEB01_0102/01/2001

Kubota designed a hydrostatic transmission for a compact tractor to improve operator control and increase efficiency and productivity. Compact tractors with 15-30 kW (20-40 hp) power takeoff (PTO) are used in a wide range of applications, such as light-duty construction, farming, and lawn mowing. Customers include homeowners, professional contractors, and equipment rental businesses. In such operations, tractors are expected to be highly convenient and easy to operate. One of the major implements for this class of tractors is the front-end loader; use estimates range to 70% of job categories. With a front-end loader, the tractor operator controls the loader with the right hand and the steering with the left hand. For switching between forward and reverse, an operator with a conventional transmission must remove the left hand from the steering wheel to grasp the forward/reverse lever. Frequent shifting between forward and reverse adds to the operator's workload. Hydrostatic

Improved Reliability Brake Pneumatic Drive

2000-01-263909/11/2000

The main requirements to which the brake system of a vehicle should respond are provision of the standard operation speed and protection features of the control pneumatic drive in case of a malfunction of any of its elements. The article describes a design of modified pneumatic brake drive having improved protection properties in case of damage of a diaphragm of any brake chambers, and methodology of parameter optimization of such drive allowing to create a layout of drive assemblies with the necessary operation speed for MAZ truck-based road trains.

Uspenskiy, Alexander, Pavlovich, Alexander

Switching Type Control of Hydraulic Drives - a Promising Perspective for Advanced Actuation in Agricultural Machinery

2000-01-255909/11/2000

Further advances in agricultural machinery require - amongst others - means for fast and precise positioning. Hydraulic drives fit very well to the environmental conditions of this machinery and can provide the required performance. State of the art methods of fluid power control by servo or proportional valve technology are not adequate for cost and maintenance reasons. Switching techniques are an alternative. Various concepts of switching exist. Some of these also show good efficiency. To put these techniques to practice requires very fast switching valves which currently are not available. One promising concept to realize such valves is outlined.

Scheidl, R., Garstenauer, M., Manhartsgruber, B.

Claas CVT Development for Different Applications in Commercial Vehicles

2000-01-264209/11/2000

Claas Industrietechnik (CIT), the component company in the Claas group active in the market segment of agricultural machines, looks back on 12 years' experience in the development, production and use of continuously variable transmissions. This paper summarizes the company's experience and presents TRAXION, a new model range in transmissions that has resulted from it. Beginning with the target markets and vehicle applications, it will demonstrate the demands made on the transmissions, the concept chosen and the manner of operation. Moreover, the presentation provides insights into the electronic controls and their development. The contents of the test program, the test stands and vehicles required as well as preliminary results will round off the picture.

Blumenthal, Ulrich, Hansen, Thomas, Obermeier-Hartmann, Robert

Development of the Kubota “New Grand L” Series Compact Tractors

1999-01-279701/13/1999

In 1998, Kubota Corporation introduced the second generation compact tractors we call the New Grand L Series to the global market. This series comes in four basic models with the power-take-off (PTO) output ranging from 19.1 to 28.0 kW (25.6 to 37.5 HP). These models retain the compact size and high HP output, which were the basic concepts of the Grand L series first launched in 1994. The second generation Tractors are equipped with a newly designed hydrostatic transmission (HST), and a operator friendly cab with an improved air conditioner system and excellent visibility. These new generation compact tractors feature improved control and comfort which results in high efficiency and excellent productivity. This paper discusses the engineering steps, proven results and brings out noteworthy features of the Hydrostatic Transmission system and the climate-controlled cab of the New Generation Grand L Series tractors (Table.1).

Nishi, Keishiro, Toshikuni, Nobuyuki, Sato, Kenichi, Nagasawa, Shota

Hydrostatic Drives in Heavy Mobile Machinery–New Concepts and Development Trends

98198909/14/1998

The use of hydrostatic transmission as vehicle drives is primarily motivated by its large range of continuously variable speed, high maneuverability and a possibility to increase the overall efficiency. Consequently an optimally designed system can provide low fuel consumption and thereby low exhaust gas emission. Modern technology involving electro-hydraulic systems, microprocessor control and control theory makes it easier to utilize the advantage of these properties than using traditional hydro-mechanical control. The requirements on productivity are very high for mobile machinery. High output capacity and a wide velocity range are therefore of great importance. To meet these requirements an ordinary hydrostatic transmission is generally used with a mechanical gearbox connected in series. The main drawback in this concept is the high cost in using a gearbox, which can switch gear ratios without jerks and other disturbances in speed and torque transmission. By joining pumps, motors

Rydberg, Karl-Erik

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