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Includes oil specifications, contamination and pressure-check procedures, valve plate and pump/motor identification cautions, and guidance for charge pump setup, control shaft use, and common motor-section failure points.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/technology/","Technology",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/sundstrand-hydrostatic-systems-supplemental-information-introduction-service-notes/664353/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/sundstrand-hydrostatic-systems-supplemental-information-introduction-service-notes/664353.png","ImageObject",300,407,{"name":42,"@type":43},"The UK Girl","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-30","2026-10-29",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",5,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What oil types are recommended for the transmission, and what is the key caution?","Question",{"text":63,"@type":64},"Use SAE 10W-30 or SAE 10W-40 engine oil. Some 1972 and prior (and some 1973) units use automatic transmission fluid (Dexron II); do not mix engine oil and automatic transmission fluid, and fully clean the system to convert.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"Why can an unsealed condition lead to low or no charge pressure?",{"text":68,"@type":64},"Any unsealed condition in the transmission can cause low-or-no charge pressure. The manual notes that many loss-of-pressure issues are due to stuck acceleration or forward/reverse check valves, charge pressure relief valves, or motor-section component failures.",{"name":70,"@type":61,"acceptedAnswer":71},"How should the charge pump be installed to avoid malfunction?",{"text":72,"@type":64},"With the pump end cap positioned as shown, ensure the dowel pin is down nearest the end cap sealing surface. The charge pump must not be installed upside-down; also confirm the needle bearing protrudes above the housing surface and that the valve plate notch is correctly placed over the dowel pin during assembly.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},664353,1793252185,{"code":4,"msg":82,"data":83},"success",[84,88,92,96,100,104,109,114,119,122,126],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & 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INFORMATION\n\n\n| SUPPLEMENT   |\n| --- |\n| SUPPLEMENT   |\n| SUPPLEMENT   |\n\n# INTRODUCTION\n\nThe following information will assist you with troubleshooting,assembly,and repair information,in light of changes made and experience gained since thismanual was first published in 1974.It also contains special service information for1978-82 model year Sundstrand units.  \n# SERVICE AND REPAIR PARTS\n\nHydrogear Conversions -Many hydrogear units (1966 to mid-1973)have been converted to the serviceable piston-piston transmission.Refer to the photos in this manual to identify the transmission in aparticular tractor.  \nComplete Transmissions-Complete replacement transmissionassemblies are no longer available.Independent outside rebuildingservice many be available.Refer to the latest issue of ServiceBulletin 437 for information.  \nRepair Parts -Use this manual to determine replacement partnumbers for 1965 to mid-1973 hydrogear units(Pages 54-56)andmid-1973 to 1977 piston-piston units(Pages 60-62).Be sure tocheck parts price list to determine if all parts needed are stillavailable before ordering parts.  \nPiston-piston part numbers for 1978-82 model year tractors arecontained in the particular tractor parts manual.  \nD-Series Adjustments -Transmission control linkage adjustments  \ndescribed in this manual for 1975 models are appropriate for 1976-  \n77 models.1978-82 linkage adjustments are covered in the 1978-79  \nB,C,D-Series Service Manual,P/N 810063R1.  \nD-Series Driven Coupling Preload and Pump Alignment -Refer toService Bulletins 217 and 305 for special service information.  \nCONSTRUCTION CHANGES,1978 AND LATER  \nSundstrand units on 1978 and later tractors differ from earlier units inthat the motor shaft extends through the cover plate,for themounting of a parking brake drum.Motor repair operations  \ndescribed in this manual still apply,except that the motor cover plateoil seal should be replaced during the repair process.  \nC  \nC  \nu  \nPart-way through the 1979 model year,the charge pressure relief valveon hydraulic lift models was changed from ball-type to cone-type.Bothconstructions are illustrated below,with part numbers given for thecone-type valve system.  \n\n| SUPPLEMENT   |\n| --- |\n| SUPPLEMENT   |\n| SUPPLEMENT   |\n\n# SERVICE NOTES\n\nOil-The recommended transmission oil is SAE 10W-30 or SAE 10W-40engine oil.IMPORTANT:All 1972 and prior,and some 1973 modelsuse automatic transmission fluid(Dexron II).Determine type of oil inthese units -Do Not Mix engine oil and automatic transmission fluid.Units may have been changed to engine oil during prior overhauls.Toconvert to engine oil,the entire system-transmission,transaxle,hoses,hydraulic lift valve -must be totally cleaned of transmission fluid.  \nPressure Checks -Keep in mind an \"unsealed\"condition anywhere inthe transmission will cause a low-or-no charge pressure condition.Troubleshooting charts and the lack of charge pressure seem to point tothe pump section as the source of the problem.Experience showsmost \"loss of pressure\"conditions to be due to:sticking acceleration orforward/reverse check valves,charge pressure relief valves,or aproblem in the motor section.Motor section problems are mostcommonly snap ring,special retaining ring,or spiraloc retaining ringfailure,causing the motor cylinder block to lose its spring preloadagainst the valve plate.  \nContamination-Where dirt or failed parts have circulated through thesystem,it is essential the entire system be disassembled and flushedclean -both transmission sections,the transaxle,hydraulic valve,andhoses or hydraulic manifold.Residual contamination will quickly destroythe repaired unit.  \n● Valve Plates -Note the difference between the pump and motor valveplates (Fig.44).Ensure the correct valve plate is ordered whenreplacing,as the motor plate willfit in place of the pump plate,but willnot function properly.Scratches i","cbCaijQ94nvOGL46","https://ap.wps.com/l/cbCaijQ94nvOGL46","pdf",5083973,34,"English","# SUPPLEMENTAL INFORMATION\n# INTRODUCTION\n# SERVICE AND REPAIR PARTS\n## CONSTRUCTION CHANGES, 1978 AND LATER\n# SERVICE NOTES","[{\"question\":\"What oil types are recommended for the transmission, and what is the key caution?\",\"answer\":\"Use SAE 10W-30 or SAE 10W-40 engine oil. Some 1972 and prior (and some 1973) units use automatic transmission fluid (Dexron II); do not mix engine oil and automatic transmission fluid, and fully clean the system to convert.\"},{\"question\":\"Why can an unsealed condition lead to low or no charge pressure?\",\"answer\":\"Any unsealed condition in the transmission can cause low-or-no charge pressure. The manual notes that many loss-of-pressure issues are due to stuck acceleration or forward/reverse check valves, charge pressure relief valves, or motor-section component failures.\"},{\"question\":\"How should the charge pump be installed to avoid malfunction?\",\"answer\":\"With the pump end cap positioned as shown, ensure the dowel pin is down nearest the end cap sealing surface. The charge pump must not be installed upside-down; also confirm the needle bearing protrudes above the housing surface and that the valve plate notch is correctly placed over the dowel pin during assembly.\"}]","SUNDSTRAND HYDROSTATIC SYSTEMS - Supplemental Information - Introduction - Service Notes | PDF",86]