Browse Topic: Hydraulic drives

Items (38)

Redundancy Control of Anti-lock Braking System Based on Electro-hydraulic Braking System

9/13/2022

As the basic function of the active safety configuration of a vehicle, the anti-lock braking system will compromise the driving safety if it fails. Based on the self-designed electro-hydraulic braking system, this article proposes an anti-lock brake redundant control architecture. The electro-hydraulic braking system is mainly composed of four parts: a brake pedal unit, a hydraulic drive unit, a brake execution unit, and a control unit. The mechanical structure is compact and exquisite, and the system has the function of precise and adjustable hydraulic pressure. The control architecture adopts a hierarchical control design, which is mainly composed of an upper wheel slip rate controller and a lower hydraulic pressure controller. Both the upper and lower controllers use a sliding mode variable structure control to improve the robustness and accuracy of the control. The upper slip rate controller outputs the desired master cylinder hydraulic pressure with the optimum slip rate of the rear wheels of the vehicle as the control target. The lower hydraulic pressure controller outputs the desired torque of the motor with the desired master cylinder hydraulic pressure as the target and achieves hydraulic pressure regulation of the master cylinder by controlling the motor motion. To verify the effectiveness of the algorithm, co-simulation and a hardware-in-the-loop test platform are built. Anti-lock braking tests are carried out under different typical working conditions: low-adhesion road, high-adhesion road, butt road, and split road. The results show that when the anti-lock braking system fails, the redundant control algorithm can achieve effective slip rate control under different driving road conditions and meets the anti-lock brake redundant control requirements. This study provides a reference for the development of low-cost anti-lock braking redundancy functions for vehicles equipped with electro-hydraulic braking systems.

Liu, Yiping, Pei, Xiaofei, Guo, Xuexun

Testing of Oxygen Equipment

ARP1398A (Current)

8/11/2021

This ARP delineates requirements for system cleanliness, test gas supply system, test stand design, environmental chamber definition, instrumentation, dynamic test equipment and testing procedures.

A-10 Aircraft Oxygen Equipment Committee

Design Approach and Dimensionless Analysis of a Differential Driving Hydraulic Free Piston Engine

2016-01-8091

9/27/2016

A new method for driving the hydraulic free piston engine is proposed. This method achieves the compression stroke automatically rather than special recovery system. Principle of hydraulic differential drive free-piston engine is analyzed and the control strategy of this novel hydraulic driving engine is also introduced. Then energy balance method is used to design the main parameters of the novel engine. High pressure and secondary high pressure of the hydraulic system are constrained by the combustion parameters and therefore parameters are analyzed. In order to verify the effectiveness of energy balance method, the mathematical model is established based on the piston force analysis and engine working principle. The transient results of dynamics are obtained through simulation. In addition, the effectiveness of the simulation is proofed by dimensionless analysis. It indicates that energy balance method realizes the basic performance of hydraulic free piston engine.

Zhang, Shuanlu, Zhao, ZhenFeng, Zhao, Changlu, Zhang, Fujun, Liu, Yuhang

Modeling and Analyzing for Hydraulic-Driven Cooling System of Heavy Duty Truck

2016-01-0222

4/5/2016

The heavy duty trucks have large engine power and drive continuously in mountainous area, so the heat dissipation of engine is very important. In the traditional cooling system with fixed transmission ratio fan, the cooling capacity is insufficient and the engine is easy to be over-heated when the engine is working in low speed and heavy load conditions. Owning to the bigger size of electric motor compared to the hydraulic motor, it is not suitably applied to the heavy duty trucks. Contrasted with the electric motor, the hydraulic drive cooling system is widely applied in heavy duty trucks due to smaller size, larger power, continuous speed modulation and flexible installation location. However, the low transmission efficiency of the pump-motor system results in high power consumption of the cooling system. In this paper, the mathematical and simulation model of hydraulic-driven fan cooling system is established for the specific engine. The study applies the digital PID controller of continuous system to control the fan. The control algorithm of anti-integral saturation is compared with the conventional method. The results show that during the time progress of 700s, the mean power consumption with anti-integral algorithm respectively reduce by an average of 40.8%, 35.1% and 29.2% in the target temperature of 363.15K, 364.15K, and 365.15K compared with the traditional control method. Moreover, the PID control with anti-integral algorithm can improve the temperature control accuracy and effectively avoid the excessive cooling.

Zhang, Xingyu, Yang, Bo, Tan, Gangfeng, Mei, Binyu, Li, Zhilei, Yang, Zhongjie, Wang, Can

The Study on Co-Simulation Based Tracked Vehicle Path Tracking Control

2015-01-1114

4/14/2015

The tracked vehicle with a fully hydraulic driving system, which has a strong traveling performance of passing and mobility ability in the complex terrain, is a typical system of mechanical-electrical-hydraulic integration. At the same time, for the good low-speed stability of the hydraulic system, this vehicle is widely applied in most engineering projects. However, for the complexity and unpredictability of the motion state in the complex environment and the power matching of the driving system, the driving path of the tracked vehicle with hydraulic driving is difficult to control. Moreover, for the complicated interaction between mechanics, the establishment of the mathematical model is much more complex, and the traditional mechanics-control and hydraulic-control co-simulation can not accurately simulate this physical phenomenon. The kinematic and dynamics characteristics of the tracked vehicle are studied firstly, and the dynamics model is built. Meanwhile, the hydraulic system is also established with the analysis of the closed loop hydraulic system. According to the kinematics and hydraulic characteristics, the path tracking controller is designed. The co-simulation model is built based on the control system. Then dynamic connections of the mechanical-electrical-hydraulic system are implemented, and the validity and stability of the control strategy and hydraulic system are verified and evaluated. The results show that the vehicle can track the path effectively in a certain range of error, and the hydraulic system has good stability and reliability. In addition, this co-simulation with mechanics and hydraulic and control system research method is proved to be feasible, which also reflects obvious advantages of modeling and control system design.

Wang, Can, Yang, Bo, Tan, Gangfeng, Wang, YiRui, Zhou, Li

Simulation Study of Hydraulic Differential Drive Free-piston Engine

2015-01-1300

4/14/2015

The hydraulic free piston engine is a complex mechanical-electro-liquid system, in order to simplify the complex system of the single hydraulic free piston engine, a new method for the driving of hydraulic free piston engine is proposed. Hydraulic differential drive achieves the compression stroke automatically rather than special recovery system. The structure and principle of hydraulic differential drive free-piston engine are analyzed and the mathematical model is established based on the piston force analysis and the hydraulic system working principle. In addition, the control strategy of this novel hydraulic driving engine is also introduced. Finally, the transient results of dynamics are obtained through simulation. Then we compare our results to the ones from the hydraulic free piston engine made by the company Innas. The results show that: 1) the simplified engine can achieve the similar performance of the Innas BV concept. 2) The maximum frequency and the maximum power of the engine are increased. 3) The indicated work of the novel engine decreases and the BSFC increases by 2.3%.

Zhang, Shuanlu, Zhao, Changlu, Zhao, ZhenFeng, Yafei, Dong, Ma, Fukang

Bosch Rexroth

13OFHD0613_136/13/2013

Manufacturing and logistical excellence Companies serving the off-highway industry face an array of challenges in the current global marketplace. While some regions are experiencing growth and demand for new equipment, other regions continue to face economic headwinds. In addition, technology challenges and regulatory events such as Tier 4 Final make it necessary for companies to be as flexible and responsive as they can to changing market needs. Manufacturers will often promote new technologies or product updates as the “right way” to solve these challenges. However, product innovation must go hand-in-hand with manufacturing and logistical excellence-because no matter how innovative a product is, it must be manufactured efficiently with the highest quality, and be delivered through flexible, efficient supply chains to achieve success. New product technology may help drive the industry, but manufacturing and logistical excellence make up the engine under the hood.

Bracht, Berend

Aerospace Pressurization System Design

AIR1168/7A (Current)

7/25/2011

The pressurization system design considerations presented in this AIR deal with human physiological requirements, characteristics of pressurization air sources, methods of controlling cabin pressure, cabin leakage control, leakage calculation methods, and methods of emergency cabin pressure release.

AC-9 Aircraft Environmental Systems Committee

Regenerative hydraulics

OFHOCT06_04

10/1/2006

The use of multiple hydraulic pumps can satisfy the needs of various circuits in off-highway equipment. With fuel prices continually on the rise, it is critical to maximize the operating efficiency of off-highway equipment. Southwest Research Institute (SwRI) continues to develop advanced electrohydraulic systems that improve vehicle efficiency. New efforts are focusing on improving the efficiency of the powertrain, the hydraulic systems, and the engine accessories that all consume significant energy during vehicle operation. Motive power is produced by powertrains to ascend grades, overcome rolling resistance, pull plows, push blades, or move harvesters through fields. Powertrain efficiency improvement is being pursued through continuously variable transmissions (CVTs), including hydraulic CVTs, to produce the maximum desired travel speed while minimizing the fuel consumed by the engine.

Stecklein, Gary

Aerospace Pressurization System Design

AIR1168/7 (Historical)

6/22/2004

AC-9 Aircraft Environmental Systems Committee

Hydraulics for economics

OFHOCT03_02

10/1/2003

The design of a digitally controlled hydraulic fan drive from Denison Hydraulics is said to help diesel engines run leaner and cleaner. One of the keys to properly and efficiently controlling emissions from diesel powered on- and off-highway machinery is maintaining the engine's optimum operating temperature. That fact plus a very important secondary benefit, reducing fuel usage, can be achieved by using an infinitely variable hydraulic fan drive. A recent solution to reducing emissions, adapted by a majority of engine suppliers to both the on- and off-highway market, has been the introduction of an electronic gas-recirculation (EGR) system. While relatively effective at reducing emissions, the EGR solution also causes considerable parasitic power loss on the engine, resulting in higher fuel consumption. As an on-highway example, an EGR system adds $5000 to $7000 per Class-8 truck application. These costs include such items as variable geometry turbochargers, additional intercoolers, and specialized valves.

Travel Performance and Rating Procedure, Crawler Mounted Hydraulic Excavators, Material Handlers, Knuckle Boom Log Loaders, and Certain Forestry Equipment

J1309_200304 (Historical)

4/24/2003

This SAE Standard describes a uniform method to calculate and specify travel performance characteristics of hydraulic excavators, material handlers, knuckle boom log loaders, delimbers, feller bunchers, harvesters, processors, and other knuckle boom material handlers. It establishes definitions and specifies machine conditions for calculations and tests. This document applies to crawler mounted machines such as hydraulic excavators as defined in SAE J/ISO 6165 and ISO 7135, and knuckle boom log loaders as defined in SAE J1209 and SAE J2055. This document also applies to certain forestry equipment defined in SAE J1209 and ISO 6814 that have crawler mountings such as delimbers, feller bunchers, harvesters, and processors. Included in the definition of hydraulic excavators are also front shovel, clamshell, and telescoping boom excavators.

MTC C5, Excavators

Switching controls in hydraulic drives

OFHOCT01_04

10/1/2001

Researchers from Johannes Kepler University believe agricultural machinery can be improved by further advances in motion generation. Proper adjustment of plow geometry is a challenging handling operation for the operator of plowing and hay-harvesting machines. The optimal values depend on the actual ground situation, which may vary. To adapt the parameters to the ground optimally, adjustment is necessary rather frequently, which realistically can be done only via remote control, or, even better, with automatic control. Current practice is to adjust manually by spindles and to use some complex kinematic mechanism to get an uncoupled relation between the position of the spindles and the relevant functional plow parameters. With full automatic control, easier operation and optimal results-both with respect to quality and performance-can be achieved. The mechanical performance characteristics of modern hay harvesters and tractors allow operation speeds of about 30 km/h (18.6 mph). At such high speeds, the driver cannot do all the necessary control. The most endangered machine part is the harvester's pick-up device, which can be damaged if it crashes into obstacles such as big stones. The rollers or sledges from which distance to ground is adjusted introduce a further complication. Even at today's operating speeds, the winding of hay around the rollers sometimes disturbs operation or damages the sward. To eliminate problems, the pick-up should be guided at a certain distance above ground by some automatic level control without mechanical contact. For high speeds, this level of control has to assure that damaging contact with obstacles is avoided by lifting the pick-up right in time. Realization of this function needs an automatic detection of distance-to-ground and of obstacles in combination with some fast response positioning drive.

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

2000-01-25599/11/2000

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.

Symbols for Hydrodynamic Drives

J640_200003 (Historical)

3/10/2000

The following system of symbols is recommended for use in technical papers and engineering reports dealing with hydrodynamic drives.

Automatic Transmission and Transaxle Committee

DESCRIPTION OF ACTUATION SYSTEMS FOR AIRCRAFT WITH FLY-BY-WIRE FLIGHT CONTROL SYSTEMS

AIR4253 (Historical)

5/1/1999

This AIR provides a description of representative state-of-the-art, fly-by-wire (FBW) actuation systems used in flight control systems of manned aircraft. It presents the basic characteristics, hardware descriptions, redundancy concepts, functional schematics, and discussions of the servo controls, failure monitoring, and fault tolerance. All existing FBW actuation systems are not described herein; however, those most representing the latest designs are included. While this AIR is intended as a reference source of information for future aircraft actuation system designs, the exclusion or omission of any other appropriate actuation system or subsystem should not limit consideration of their use on future aircraft.

A-6A3 Flight Control and Vehicle Management Systems Cmt

Swing Performance And Rating Procedure, Material Handlers, Knuckle Boom Log Loaders And Certain Forestry Equipment

J2393_199806 (Historical)

6/1/1998

This SAE Standard describes a uniform method to calculate and specify swing performance characteristics of material handlers, knuckle boom log loaders, delimbers, feller bunchers, harvesters, processors, and other knuckle boom material handlers. It establishes definitions and specifies machine conditions for calculations and tests. This document applies to knuckle boom log loaders as defined in SAE J1209 and SAE J2055 and to certain forestry equipment defined in SAE J1209 and ISO 6814 that have rotating upper-structures such as feller bunchers, harvesters, processors, and forwarders. Included in the definition of knuckle boom log loaders are behind the cab and rear-mounted log loaders not having their own power supply.

MTC4, Forestry and Logging Equipment

Hydraulic Drive Systems and Potential Use for Automobiles and Airplanes

97558110/1/1997

Utilization of hydrostatic drives for power transmission, along with hydropneumatic accumulator energy storage can provide significant opportunities for improvements in vehicle design. These advantages are particularly relevant when considering advanced concept vehicles such as flying automobiles. Research and development in this technology has primarily focused on the fuel economy improvements that can be achieved in automobiles using a hydrostatic transmission and hydropneumatic accumulator energy storage. The accumulator permits the engine power to be uncoupled from the road load, thus enabling the engine to be operated at a more efficient point. By using wheel drive units that can operate as either motors (when driving) or pumps (when braking), regenerative braking can also be achieved, with the energy stored in the accumulator. In addition to improved fuel economy, several other significant design opportunities can be exploited. The drivetrain concept that has been most extensively studied would facilitate incorporation of additional attractive features such as antilock braking and traction control. The availability of hydraulic power also facilitates the incorporation of active suspension in the vehicle. Opportunities also exist for size and weight reductions, particularly by utilizing an auxiliary hydrostatic drive unit for accessories such as the air conditioning compressor and the alternator. By operating these units at a constant (relatively high) speed, they can be much smaller and lighter that those found in conventional vehicles. The electric motor which drives the radiator fan can be replaced with a more compact, lighter hydraulic unit, and the power steering pump can be eliminated altogether. When considering even more advanced vehicle concepts, such as airplanes that could be operated as roadable vehicles, hydrostatic drive once again offers some unique advantages. The technical challenges associated with practical roadable aircraft include propulsion system weight and vehicle performance for both ground and air modes of operation. When compared to conventional drivetrains, the compact size of hydrostatic pump/motors and the relative ease of distributing the power permits significant design flexibility in locating the principle powertrain components. This design flexibility inevitably leads to easier achievement of a more aerodynamic design. Also, the flexibility of hydrostatic drive allows optimal load matching of the engine and propeller over a range of operating conditions, supporting minimal weight designs.

Fronczak, Frank J., Holmes, Bruce J., Beachley, Norman H.

Robust Control of Hydraulic Servos

9617958/1/1996

Developing controllers for hydraulic servos is difficult due to the inherent uncertainty and nonlinear characteristics of the system. Systems are classed as uncertain when they are subject to unknown parameter variations or disturbances, or when there is incomplete knowledge of the system model, all of which are common in hydraulic servo systems. However, unlike conventional control techniques, the use of modern control methods means that system uncertainty can be considered at the controller design stage, and consequently robust controllers can be developed. In this paper the robust control of hydraulic servo systems is considered, and sources of uncertainty typical in hydraulic drives are discussed. The effect of ignoring these uncertainties is demonstrated by simulation experiments of a hydraulic servo, comparing conventional control techniques to the modern approach of H∞ optimal control. The implementation of modern controllers is also discussed.

Hampson, S. P., Chawdhry, P. K., Burrows, C. R.

TRAVEL PERFORMANCE AND RATING PROCEDURE, CRAWLER MOUNTED HYDRAULIC EXCAVATORS, MATERIAL HANDLERS, KNUCKLE BOOM LOG LOADERS, AND CERTAIN FORESTRY EQUIPMENT

J1309_199606 (Historical)

6/1/1996

This SAE Standard describes a uniform method to calculate and specify travel performance characteristics of hydraulic excavators, material handlers, knuckle boom log loaders, delimbers, feller bunchers, harvesters, processors, and other knuckle boom material handlers. It establishes definitions and specifies machine conditions for calculations and tests. This document applies to crawler mounted machines such as hydraulic excavators as defined in SAE J1057 and ISO 7135, and knuckle boom log loaders as defined in SAE J1209 and SAE J2055. This document also applies to certain forestry equipment defined in SAE J1209 and ISO 6814 that have crawler mountings such as delimbers, feller bunchers, harvesters, and processors. Included in the definition of hydraulic excavators are also front shovel, clamshell, and telescoping boom excavators.

MTC C5, Excavators

Charles M. Manly: An Early American Innovator in Aircraft Engines

9505032/1/1995

During an exemplary engineering career Charles Matthews Manly (1876-1927), former president of the SAE and one of America's foremost aircraft engine pioneers, contributed greatly to the design and development of the radial piston engine, which came to dominate aircraft propulsion until the 1950s. He is best known for development and refinement of a world-class 52-hp, five-cylinder, water-cooled radial aircraft engine at the Smithsonian Institution. His early academic achievements led to his appointment as chief assistant to Professor S. P. Langley, secretary of the Smithsonian Institution, who was engaged in early aeronautic experiments and, in 1903, racing with the Wright brothers to demonstrate the first manned aeroplane. Easily the most advanced aeronautical engine in the world at the turn of the century, the so-called Manly-Balzer radial powerplant used in Langley's Aerodrome was almost 20 years ahead of its time in terms of specific-weight excellence. Manly risked his life twice in 1903 in unsuccessful attempts to fly the Aerodrome (launched from a houseboat on the Potomac River), although the engine itself performed flawlessly during these tests. After this aeronautical work, Manly diverted his talents into the design and production of variable-speed hydraulic drives, a field in which he ultimately earned about 40 U.S. patents. Maintaining his interest in aeronautics during World War I, he first served as a consultant to the British War Office and then worked in various engineering and management positions at the Curtiss aircraft concern from late 1915 to early 1920. During this time, Manly became involved with the SAE, first in 1917 and 1918 developing aircraft standards, and ultimately serving with distinction as president in 1919. Consulting automotive engineering activities (in partnership with C. B. Veal-later to become SAE's research manager) consumed the balance of his career until his premature death in 1927. In 1929 Manly was posthumously awarded the Smithsonian's prestigious Langley medal for outstanding aeronautical achievements (previously awarded to the Wright brothers, Glenn Curtiss, and Charles Lindbergh). In 1928, the SAE board of directors also honored him by originating the Manly Memorial medal for best annual SAE paper on aeronautic powerplants, which is still awarded today.

Rinek, Larry M.

AUXILIARY POWER SYSTEM CONSIDERATIONS FOR ADVANCED MILITARY AIRCRAFT

AIR1603 (Current)

6/1/1993

This document provides a brief description of the auxiliary power equipment that is available with enough description and pertinent comments to enable an engineer to make logical preliminary selection of the appropriate equipment for advanced military aircraft programs. The information has been kept as brief as possible to include the maximum amount of equipment in a relatively short document. It is not intended to replace textbook design analysis or detailed information available from the equipment suppliers. The document describes auxiliary power equipment. Auxiliary power is defined as follows: "Those elements of secondary power [defined as all aircraft nonpropulsive power generation and transmission] related to main engine bleed air and shaft power extraction or power generation separate from the main engines. Included are engine bleed air systems, remote engine driven gearboxes, engine starting systems, auxiliary power units, and emergency power systems." Additional definitions may be found in ARP906A which is the source of this definition. Some closely related systems which are not discussed in detail, include thermal management, environmental control, electrical, and hydraulic systems.

AE-6 Starting Systems and Auxiliary Power Committee

Electrohydraulic Loadsensing

9118149/1/1991

Valve-controlled hydraulic drives are frequently used when high dynamics, high reliability and a compact structural form are required. A disadvantage which is frequently attributed to a valve-controlled drive is its poor running efficiency. It not only leads to higher energy consumption but - amongst other things - to the necessity of installing larger pumps and more elaborate cooling equipment. Both these factors cause an increase in the costs of hydraulic drives. Load sensing is known from the field of mobile hydraulics as a driving concept with high running efficiency. In load sensing the supply pressure is adjusted to suit the actuator's highest point of load pressure. The dynamics of this system is worse than that of systems with a constant supply pressure. Electrohydraulic load sensing offers possibilities to improve the dynamics of valve-controlled drives in load sensing by using control engineering measures.

Backé, W., Zãhe, B.

Crawler Mounted Hydraulic Excavator Travel Performance

J1309_199105 (Historical)

5/1/1991

This SAE Standard provides a uniform method for calculating and specifying travel performance characteristics of hydrostatically driven crawler mounted hydraulic excavators as defined in SAE J1057.

MTC C5, Excavators

Sealing of Pressurised Media in Automotive Applications for Rotating Shafts

8604902/1/1986

The rubber industry provides special oil seals from elastomeric materials to seal pressurised shaft applications. Normally these are small and simple looking devices, which can tolerate quite complex conditions. The design of the seal has a tremendous impact on good performance. Basic parameters for pressure oil seals made from elastomeric materials will presented. Application conditions must be balanced to the degree of seal stress. For example the right compromise has to be chosen for flexibility and stability of the lip section. The heat which is generated by friction must be dissipated through the shaft and the medium to be sealed. Medium and elastomeric material must not be overloaded thermally. The product of pressure and surface speed (p · v) is an important characteristic for the evaluation of how much a seal is stressed. A graph of achievable ‘p · v’-figures will be presented. In general pressure applications require closer attention to material selection than general purpose seals. Pressure oil seals for automotive applications will be presented with examples for power steering, hydraulic drive units and a tire inflation system.

Rapp, Hermann, Forch, Hans

Opportunities and Challenges for Electric-Drive Systems on Aircraft

84162710/1/1984

Traditionally, aircraft systems have relied upon bleed air from the main engine as the primary energy source for environmental control systems (ECS) and anti-icing systems. With the next generation of engines, bleed air may not be available to the extent utilized in the past. Electric drive systems are now being considered as viable alternatives for ECS. Electric drives are also being considered for traditional hydraulic drives in applications such as engine fuel pumps, and flap actuators. Several aspects of electric drive systems consisting of permanent-magnet motors (PMM's) and solid-state power electronics for the primary generation or secondary control of electric drives on aircraft are discussed in this paper. For power distribution, conventional 120/208-v, 3-phase, 400-Hz; 270-vdc, variable frequency/constant voltage, and variable frequency/variable voltage systems are the primary candidates. Specific examples on 270-vdc power generation, variable speed drives for an ECS compressor and fan motors, and a variable speed drive for an engine fuel pump system are also included. Many opportunities and challenges exist and are being acted upon. Together they provide the interest necessary for the timely development of the technology for electric drive systems on aircraft.

Beauchamp, Edward D.

CRAWLER MOUNTED HYDRAULIC EXCAVATOR TRAVEL PERFORMANCE

J1309_198303 (Historical)

3/1/1983

This recommended practice applies to hydraulic excavators as defined in SAE Standard J1057, which are crawler mounted. It describes the methods for calculating and specifying travel performance characteristics. It does not apply to wheel mounted excavators.

MTC C5, Excavators