SAE TECHNICAL PAPER SERIES Load Sensing Fluid Power Systems Yasuo Aoki, Kazuo Uehara, Kazuyuki Hirose, Tadao Karakama, Kouichi Morita, Teruo Akiyama, and Yesuke Oda Komatsu Ltd. The Engineering Society International Off-Highway & *lli =For Advancing Mobility and Sea Air and Space, Powerplant Congress & Exposition INTERNATIONAL Milwaukee, Wisconsin September 12-1 4,1994 400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (41 2)776-4841 Fax:(412)776-5760 Downloaded from SAE International by Imperial College London, Monday, September 24, 2018The appearanceof the ISSN code at the bottom of this page indicates SAE's consent that copies of the paper may be made for personal or internal use of specific clients. Thisconsent is given on thecondition, however, that the copierpaya$6.00 per article copy fee through the Copyright Clearance Center, Inc. Operations Center, 222 Rosewood Drive, Danvers, MA 01 923forcopying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collective works, or for resale. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Service Department. To obtain quantity reprint rates, permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, contact the SAE Publications Group at (41 2) 776-4841. GLOBAL MOBlUTY DATABASE A11 SAE papers, standards, and selected books are abstracted and indexed in the Global Mobility Database. No part of this publication may by reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. ISSN 0148-7191 Copyright 1994 Society of Automotive Engineers, Inc. Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE transactions. For permission to publish this paper in full or in part, contact the SAE Publications Group. Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Activity Board, SAE. Printed in USA ~O.IX)~C/PG Downloaded from SAE International by Imperial College London, Monday, September 24, 2018Load Sensing Fluid Power Systems Yasuo Aoki, Kazuo Uehara, Kazuyuki Hirose, Tadao Karakama, Kouichi Morita, Teruo Akiyama, and Yosuke Oda Komatsu Ltd. ABSTRACT Cl osed-Center-type Load Sensing Systems for fluid power controls in hydraulic excavators, which had been considered as far back as 1955, were proposed in the U.S.A. in 1975, but were not feasible. In the late of 1980's European-made hydraulic excavators were equipped with load sens- ing systems, including flow dividing control. In the early 19901s, further improvement of CLSS's were made in Japan. CLSS's are capable of control 1 ing complex mo- tions of mu1 tiple actuators with high accuracy against varying loads under varying engine speed conditions, with expectations for improved control - 1 abi 1 i ty and compat i bi 1 i ty of hydraul ic excavators to many kinds of works in which attachments are used. Conversely, operators have made the best use of the characteristics of conventional fluid power systems, in which each actuator speed is varied by inertia or engine speed change. Accordingly in 1993, Komatsu Ltd. introduced a range of new hydraulic excavators, equipped with newly-developped CLSS's, which are sui tab1 e for either traditional excavator use or new electrical operation, incl uding automatic electronic control by microcomputer. 1