"service manual"
Contents
1. 4ZU Force Magnification To gain a mechanical advantage the size of the ends of the container can be varied Example The pump has an area of 1 square inch The cylinder has an area of 10 square inches If 10 pounds of force is applied to the pump 100 pounds of force is exerted on the cylinder If the amount of work put into the system equals the amount of work out of the system 10096 efficient the pump will travel 10 times farther than the cylinder 3 4297 421 Building A Basic Circuit Let s put together a simple circuit using some basic hydraulic components We will start out with a simple pump and cylinder connected by a line As you can see there are some flaws in this design There is not extra oil so that the pump can continue raising the cylinder after the first stroke Also when the pump handle is raised the cylinder drops 3 4297 422 17 Productivity Series HYDRAULICS UNDERSTANDING CIRCUITS The flaws can be corrected by installing a reservoir and two check valves One check valve will keep oil from being forced back into the reservoir and the second will keep the oil under the cylinder when the pump handle is raised When the pump arm is raised the surface area of the chamber between the check valves increases As the area increases pressure acting on the surfaces inside the chamber decreases When the pressure in the reservoir becomes greater than the spring pressure on the c2. Hydraulic hoses or lines can be routed around corners A mechanical system would require a complex belt chain or gear system to accomplish this The same fluid that transfers the energy also provides lubrication for moving parts There is a greater need for lubrication between moving parts under heavy load With hydraulics as the load increases so does the operating pressure This automatically provides maximum lubrication during periods of higher loads INTRODUCTION HYDRAULICS How We Use Hydraulics Applications for hydraulics are diverse throughout industry With lawn and garden equipment the main uses are to 1 Propel the unit 2 Lift implements attached to the unit 1 1311 19 5 Productivity Series HYDRAULICS TERMS AND COMPONENTS FN The first step in becoming comfortable with hydraulics is to learn the language This section provides descriptions and examples of common hydraulic terms and components We will first define some of the common terms used when working with hydraulics Then we will describe the components which are included in many of the hydraulic systems you encounter The review section at the end of the chapter will test your knowledge of the terms and components HYDRAULIC TERMS Hydraulics Hydrodynamics Hydrostatics Hydraulics refer to applications of liquids in motion In all of our uses liquids refer to oil Hydrodynamics refer to
3. This symbol means WARNING or PERSONAL SAFETY INSTRUCTION read the instruction because it has to do with your safety Failure to comply with the instruction may result in personal injury or even death Aways read and follow the safety instructions provided in the applicable service manual or operators manual for the equipment you are working on Service SAFETY INFORMATION Manuals and Operator s Manuals are available through your local Toro distributor or by writing to The Toro Company Publications Department 8111 Lydale Avanue South Bloomington MN 55420 Avoid injury from high pressure oil Keep body and hands away from pin hole leaks or nozzles that eject high pressure oil Use cardboard or paper to locate hydraulic leaks Oil escaping under high pressure can penetrate the skin and cause injury Oil accidentally injected into the skin must be surgically removed within a few hours by a doctor familiar with this form of injury or gangrene may result Avoid unexpected starting of engine Always turn off the engine and disconnect the spark plug wire s before cleaning adjusting or repairing Avoid lacerations and amputations Stay clear of all moving parts whenever the engine is running Treat all normally moving parts as if they were moving whenever the engine is running or has the potential to start Avoid burns Do not touch the engine muffler or other components which may increase in temperat
4. 3 4297 431 Productivity Series 20 UNDERSTANDING CIRCUITS HYDRAULICS Building A Drive System Let s replace the cylinder with another type of actuator a fixed displacement hydraulic motor With the motor in place this system will provide the continuous mechanical energy output needed to propel lawn and garden equipment This system can reverse the direction of travel by changing the spool offset and reversing the oil flow through the motor Notice that there is nothing in this system that will allow the output speed to be changed 3 4297 432 Our hydrostatic drive systems use a variable displacement pump and a fixed displacement motor With variable output from the pump the spool valve is no longer needed to control the direction of oil flow The speed can also be changed with this variable output pump 3 4297 433 The Real Thin If we combine the drive system with the lift system we had previously the result is a hydraulic system similar to systems on many of the larger tractors in use today 3 4297 434 21 Productivity Series HYDRAULICS REVIEW SECTION 2 1 Under load which pressure gauge A or B below will indicate the most pressure 2 If both circuits below have the same amount of pressure applied to them which circuit A or B is capable of lifting more weight 3 Which valve A B or C in the circuit below
5. A push valve is a flow control valve used to open a pump motor circuit Manually opening the circuit allows oil to bypass from one side of the circuit to the other or allows oil to escape back to the reservoir The push valve allows the unit to be moved MOTOR gy N without starting the engine Most but not all hydrostatic transmissions use a push valve 3 4297 412 Relief Vaive A relief valve is a pressure control valve which is used to protect a hydraulic circuit from pressures which are higher than the circuit s design 3 4297 413 13 Productivity Series HYDRAULICS TERMS AND COMPONENTS OPEN CLOSED CENTER CENTER 3 4297 414 HYDRAULIC PRESSURE MECHANICAL ENERGY HYDRAULIC FLOW 3 4297 415 3 4297 416 Productivity Series Spool Valve A spool valve is a directional valve used to control oil flow There are two types of spool valves open center and closed center Both types allow oil flow to be diverted to a remote circuit when the spool is not centered A closed center spool valve stops flow from the pump when it is centered This type of valve is not used with a positive displacement pump An open center spool valve allows oil from the pump to pass through the valve when the spool is centered Actuator A hydraulic actuator is a device which converts hydraulic pressure and flow into mechanical energy The two most common types of actuators are hydrostatic motors and hy
6. hydraulic systems which primarily use fluid flow to transfer energy This includes applications such as a water wheel or a torque converter Hydrostatics refer to hydraulic systems which primarily use fluid pressure to transfer energy This includes applications such as a hydraulic lift system or fluid powered transmission All of our applications involve hydrostatics 9 4291 400 Work Work is the application of a force through a distance For any work to be accomplished movement is needed Work is typically measured in foot pounds ft Ibs Work Force X Distance 50 ft lps Example The same amount of work is done if a 5 pound object is moved 10 feet or if a 10 pound object is moved 5 feet 5t 10 Ibs 3 2714 400 Productivity Series TERMS AND COMPONENTS HYDRAULIC TERMS cont d Power Power is the rate at which work is done or energy is transferred Power is measured in foot pounds per second ft Ibs sec Power z Work Time One horsepower is equal to 550 ft Ibs sec Moving 55 pounds 10 feet in one second takes one horsepower In hydraulics to transmit power two factors must be present pressure and flow Power z Pressure X Flow Pressure l i Pressure provides the potential to transmit energy It is determined by the force across an area Pressure is measured in pounds per square inch psi Pressure Force Area Ten pounds of force acting on one square in
7. s replace the hand pump with an external gear pump which is capable of providing constant displacement and more flow By placing the pump in line we no longer need the check valves to provide directional control The greater output of this pump will extend the cylinder much faster When the cylinder ram reaches the end of its stroke pressure will increase and open the relief valve 3 4297 427 If we replace the single action cylinder with an open center spool vaive and a dual action cylinder we have a basic lift system When the spool valve is centered the oil passes directly through it and returns to the reservoir 3 4297 428 19 Productivity Series HYDRAULIES UNDERSTANDING CIRCUITS a When the spool valve is offset oil is directed into the bottom end of the cylinder and the piston rod is extended Notice that oil from the opposite side of the piston also passes through the spool valve and back to the reservoir Wd 3 4297 429 When the pressure in the cylinder reaches the setting of the pressure relief valve the valve opens and directs the oil flow back to the reservoir This happens when a high resistance is met such as the cylinder reaching the end of its stroke 3 4297 430 When the spool valve is offset in the opposite direction the oil flow through the valve and cylinder is reversed AN
8. 1311 5 LII MY etm ed 1 1311 6 Productivity Series Eaton Model 781 This transaxle is used as a pair RH amp LH to make up a complete drive system It has a variable radial ball piston pump and fixed displacement radial ball motor Maximum pump output is 0 465 cu in 7 62 cc per revolution The motor output is 0 767 cu in 12 57 cc per revolution It does not use a charge pump A remote expansion tank is used for a reservoir with a fine screen at the bottom of the inlet line providing the filtration of incoming oil Two sets of planetary reduction gears provide power to the axle Hydro Gear 316 0500 This is a typical hydrostatic transaxle used in a lawn tractor It is completely self contained and has its own differential This transaxle utilizes a variable axial piston pump with a maximum displacement of 0 61 cu in 10 cc per revolution The motor is also an axial piston design with a fixed displacement of 1 28 cu in 21 cc per revolution Hydro Gear 316 0750 This hydrostatic transaxle is similar to the 316 0500 It uses a heavier differential to handle higher loads This transaxle utilizes a variable axial piston pump with a maximum displacement of 0 61 cu in 10 cc per revolution The motor is also an axial piston design with a fixed displacement of 1 28 cu in 21 cc per revolution 24 SPECIFICATIONS HYDRAULICS Hydro Gear BDP 10 This pump is a variable output axial piston
9. M a M MM M HYDRAULICS TABLE OF CONTENTS REVIEW SECTION 42 lesse RI 22 SPECIFICATIONS Eaton MOOI 7 55a eo Oe ESSO eec A beo E RR I 23 Eaton Modal ET usn ce E Res ak o bau 23 Eaton Model 781 ttn eh e e OC Rb ae le US ORDRE lo de 24 Hydro Gear 316 0500 0 0 ect nnn 24 Hydro Gear 316 0750 oki ko xs x Xe kr ca RR RR Rr 24 Hydro Gear BDP 10 css e er RE DUREE Eae 25 Ross MF Series Wheel Motor 00 000 llle eee 25 Sundstrand Series 15 C P EE N EEE 25 Tuff Tor KOIA ci s mobs neces X Rp e biet emis 26 PROBLEM SOLVING Step 1 Ask The Operator 0 0 0 cece cece eens 27 Step 2 Study The Available Information LL 27 Step 3 Inspect The Machine 0 00 e cece eee eee 28 Step 4 Operate the Machine to Verify 00000 eee 28 Step 5 List The Possible Causes 0 0000 c eeu nunana 29 Step 6 Test Possible Causes 0 0 ccc eee e eee aes 29 TEST EQUIPMENT Inlet Outlet H6s6 5 12425 SEE cobs EE ERE EU SIS keen wees 30 Pressure Gauge sev io eR ns Ra CR een ER REIR RR 30 Flow Meter Load Valve ccc eee eee nh 31 Test Equipment Needs 0 0 cee ee eee en 31 REVIEW SECTION 4 3 hii oO a pea res deme E EE 32 REVIEW SECTION ANSWERS 0 000 eee ee eee 33 Productivity Series What s In This Book This publication is designed to familiari
10. N Whats In This BOOK cos sedet vete x E REE E he ORR os 3 Why Should Read This Book 0 0 00 e eee eee eeu 3 The Basic Principle of Hydraulics 0 0 0 0 cece eee aes 4 Benefits of Hydraulics 0 lille ce cece eens 4 How We Use Hydraulics TEM 5 TERMS AND COMPONENTS HYDRAULIC TERMS Hydraulics Hydrodynamics Hydrostatics 6 WOK odd onead Douce Needed pd ga Moe ed det cL rs 6 POWO MP MEETS 7 PICSSUIC MR 7 PIOW X odas hw dops e sredar ou dm d int aure pas le tate RU eM uds 7 ETMCION CY x at eb dF ua EU eret RII xe sid ates es om tuts 8 HYDRAULIC COMPONENTS Rl EET 8 m gi Mec HC 8 Purnp FUNCION o a Sr ie E ES Res madens dad 9 PUMPS By TYDS sr suet ed ce Can Wa the aoe eae ot 9 Valve FUnctlono esa ete pr ee ee Ca XA DEREN E PELA 11 Valves By Name sseleeeeeee rn 12 ACAO 5 255 545 s uem ee ack wa ware qe EMEN Rud 14 Actuators By Type cou enine bx xe ws Slaw bee seas 14 REVIEW SECTION 4 1 seeee eee eee eens 16 UNDERSTANDING CIRCUITS Properties Of Liquids 0 0 cc cc cece cece nena 17 Force Magnification 0 00 ccc eee cece een eeees 17 Building A Basic Circuit 0 00 c cece eee eae ates 17 Building A Lift System 0 0 cece eee eee eee 19 Building A Drive System 0 cece eee eee ee 21 The Real Thing 2 cecseeeeeeceeees TEM 21 AUN 1 Productivity Series
11. PRODUCTIVITY SERIES HYDRAULICS Table of Contents Page 1 of 2 ABOUT THIS MANUAL SAFETY INFORMATION INTRODUCTION WHAT S IN THIS BOOK WHY SHOULD I READ THIS BOOK THE BASIC PRINCIPLE OF HYDRAULICS BENEFITS OF HYDRAULICS HOW WE USE HYDRAULICS TERMS AND COMPONENTS HYDRAULIC TERMS HYDRAULICS HYDRODYNAMICS HYDROSTATICS WORK POWER PRESSURE FLOW EFFICIENCY HYDRAULIC COMPONENTS RESERVOIR FILTER PUMP FUNCTION PUMPS BY TYPE VALVE FUNCTION VALVES BY NAME ACTUATOR ACTUATORS BY TYPE REVIEW SECTION 1 UNDERSTANDING CIRCUITS PROPERTIES OF LIQUIDS FORCE MAGNIFICATION BUILDING A BASIC CIRCUIT BUILDING A LIFT SYSTEM BUILDING A DRIVE SYSTEM THE REAL THING REVIEW SECTION 2 SPECIFICATIONS EATON MODEL 7 EATON MODEL 11 EATON MODEL 781 HYDRO GEAR 316 0500 HYDRO GEAR 316 0750 PRODUCTIVITY SERIES HYDRAULICS Table of Contents Page 2 of 2 SPECIFICATIONS Continued HYDRO GEAR BDP 10 ROSS MF SERIES WHEEL MOTOR SUNDSTRAND SERIES 15 TUFF TORQ K61A PROBLEM SOLVING STEP 1 ASK THE OPERATOR STEP 2 STUDY THE AVAILABLE INFORMATION STEP 3 INSPECT THE MACHINE STEP 4 OPERATE THE MACHINE TO VERIFY STEP 5 LIST THE POSSIBLE CAUSES STEP 6 TEST POSSIBLE CAUSES TEST EQUIPMENT INLET OUTLET HOSE PRESSURE GAUGE FLOW METER LOAD VALVE TEST EQUIPMENT NEEDS REVIEW SECTION 3 REVIEW SECTION ANSWERS REVIEW SECTION 1 REVIEW SECTION 2 REVIEW SECTION 3 PRODUCTIVITY SERIES HYDRAULICS
12. alve can control the rate at which oil enters or leaves the cylinder This allows the speed at which the cylinder extends or retracts to be regulated With a transaxle a flow control valve may restrict flow through a passage completely during normal operation but when activated allow oil to pass through so the unit can be hand pushed 3 4297 409 Valves By Name Acceleration Valve An acceleration valve is a special flow control valve used in some hydrostatic transmissions to smooth changes in speed or direction A common way to do this is by temporarily allowing some oil to escape from the high pressure side to the low pressure side of the pump motor circuit One example of an acceleration valve uses a small metering hole which slowly allows high pressure oil to enter the cavity behind the valve As the cavity is filled the valve advances and closes the passage between the high and low pressure circuits 3 4297 410 Productivity Series 12 TERMS AND COMPONENTS HYDRAULICS HYDRAULIC COMPONENTS cont d Check Valve A check valve can be used for pressure control or directional control It usually consists of a ball and seat area A spring may be used to hold the ball on the seat Some check valves are adjustable This is accomplished by using a spring with a different rate shimming the existing spring or compressing the spring with a threaded adjuster 3 4297 411 Push Valve
13. be necessary 29 HYDRAULICS Possible Causes Charge pump failing low output Internal cylinder leakage Spool valve problem Hose kinked Relief valve problem Spool valve linkage Check The Easy Things First Hose kinked easy Spool valve linkage veasy Charge pump failing low output Relief valve problem Internal cylinder leakage Spool valve problem Productivity Series HYDRAULICS bri EQUIPMENT _ g A PD b 1 1811 14 1 1311 15 Productivity Series To properly troubleshoot many hydraulic systems it is necessary to measure the pressure and or flow at various points in the system This can only be done by using the proper test equipment Service and repair manuals will indicate if there are specific tests which can be performed on a specific hydraulic system The amount of pressure and or flow the system should be generating will determine the size and type of the equipment needed Inlet Outlet Hose Hoses are used to connect your test equipment into the system you are testing The hoses should be rated higher than any pressure that may be reached during testing They should also be long enough to allow for easy reading of the test equipment Adapter fittings may be needed to attach to different systems Pressure Gauge As you might expect pressure gauges are used to measure the pressures experienced during certain phases of circuit operation A g
14. ch provides 10 psi of pressure Increasing the load on a hydraulic system will increase the operating pressure of the system In a hydrostatic transmission higher pressures will be generated going uphill as compared to going downhill Flow Lal Me c E REED UE nnn s Flow measures the transfer rate velocity of a liquid passing through a given cross sectional area Flow is measured in gallons per minute gpm Flow z Area X Velocity Flow Volume Time The flow rate of a hydraulic system determines the speed at which the system operates HYDRAULICS Horsepower 10 ft 55 Ibs second 3 4297 435 Flow Rate vs System Speed Flow Hate cwm speed Productivity Series HYDRAULICS TERMS AND COMPONENTS Efficiency describes the amount of power output from the hydraulic system as compared Heat Rise to the amount of power put into it Most hydraulic pumps and motors operate between 80 to 90 efficiency The loss of power is made up by leakage and fluid friction This friction causes a heat rise in the system As a pump or motor wears internally it becomes less efficient and the operating temperature increases Power In Power Out Heat Rise HYDRAULIC COMPONENTS Reservoir The reservoir is a simple yet very important component of any hydraulic system It serves as an expansion chamber and separates trapped air from the fl
15. d the same amount of pressure because they are in the same circuit CN 2 Circuit A Force is equal to pressure times the area on which it is acting The pressure is the same in both circuits The cylinder in circuit A is larger than the cylinder in circuit B The same pressure times a larger area will generate the most force 3 Valve C Valve A is a check valve which keeps oils from returning to the reservoir during pumping Valve B keeps the oil trapped under the lift cylinder Valve C is used as a pressure relief valve and as a flow control valve to let the cylinder down Review Section 3 D C A easy load o Du ae UL a oo pressures 33 Productivity Series ABOUT THIS MANUAL HYDRAULICS This Productivity Series Manual was written as a training guide for service technicians Learning the fundamentals of a subject is a necessary step in becoming an expert in any area This publication is designed to increase the readers knowledge on hydraulics The Toro Company has made every effort to make the information in this manual complete and correct We are hopeful that you will find this manual a valuable addition to your service shop If you have any questions or comments regarding this manual please contact us at the following address The Toro Company Consumer Service Training Department 8111 Lyndale Ave S Bloomington MN 55420 The Toro Company reserves the right to change product specifications or this man
16. design with a maximum output of 0 61 cu in 10 cc per revolution This pump uses a gerotor charge pump to pre charge the system a This is used in a separated pump and wheel motor system Hydraulic lines connect the pump with a wheel motor T ipods 7 1 1311 10 Ross MF Series Wheel Motor The Ross wheel motor is an internal gear gerotor design The displacement is 12 cu in rev 196 7cc rev A separate pump is used to provide the pressure and flow to this motor A small displacement pump is used to drive the wheel motor The pump must complete several revolutions to displace enough oil to drive the wheel motor through one revolution This provides a speed reduction similar to using reduction gears in a mechanical transmission 1 1311 11 Sundstrand Series 15 The Sundstrand Series 15 uses an axial piston variable pump with a fixed displacement axial piston motor The maximum pump output is 91cu in 14 9 cc per revolution and the motor displacement is 91cu in 14 9 cc per revolution An internal gear gerotor charge pump provides 4 6 gal min 17 4 l min 33 cu in per revolution 5 4 cc rev flow for use with a hydraulic attachment lift 1 1311 8 25 Productivity Series HYDRAULICS SPECIFICATIONS Tuff Torq K61A This transaxle is completely self contained and has its own differential It utilizes a variable axial piston pump and with a fixed dispacement axial piston motor A
17. draulic cylinders Actuators By Type A Motor is simply a pump used backwards It takes hydraulic pressure and flow from a pump and converts it back into rotary mechanical energy Due to their similarities in function many motors use designs similar to pumps In some cases the exact same configuration can be used as a pump or motor 14 TERMS AND COMPONENTS HYDRAULICS HYDRAULIC COMPONENTS cont d Hydraulic Cylinder A hydraulic cylinder converts hydraulic pressure and flow into linear mechanical energy It consists of a sealed chamber piston and piston rod Cylinders can CHAMBER PISTON be either single action or dual action PISTON ROD 3 4297 417 Single Action Cylinder Single action cylinders can only be powered in one direction Gravity or spring pressure is used to retract the cylinder after extension These cylinders come in two different styles The typical version has a hydraulic line connected on one side of the piston and is vented to the atmosphere on the opposite side A displacement cylinder uses a large shaft called a ram which replaces the piston and piston rod It can be serviced externally and eliminates the need for an atmospheric vent 3 4297 418 Dual Action Cylinder A dual action cylinder can be filled with oil on either side of the piston To extend the piston rod oil is forced into the bottom end of the cylinder and oil ahead of the piston is push
18. ed out of the cylinder During retraction this process is reversed allowing the piston rod to be powered in both directions A typical double action cylinder can exert more force during extension than it can during retraction This is because the piston rod takes away from the piston surface area used to retract the cylinder Force Pressure X Area 3 4297 419 15 Productivity Series HYDRAULICS REVIEW SECTION 1 o NOAA wD 9 In hydraulic systems energy from an external source is converted into hydraulic and flow As the load on a hydraulic system is increased the operating increases refer to hydraulic systems which primarily use fluid pressure to transfer energy Work is the application of a force through a Power is the rate at which is done or energy is transferred Flow is usually measured in per NET An external gear pump isa _ _ displacement pump List the three functions that a valve may perform 1 2 e 3 A hydraulic actuator converts hydraulic pressure and flow into 10 A cylinder can only be powered in one direction Productivity Series 16 UNDERSTANDING CIRCUITS HYDRAULICS Properties Of Liquids A liquid has no shape it always assumes th shape of its container Unlike air liquids compress only slightly under pressure A force applied to a contained liquid will exert equal pressure in all directions within the container 3 49
19. heck valve and the pressure in the chamber the check valve moves off its seat 3 4297 423 As oil flows into the chamber the pressure begins to increase As the handle is pushed downward the pressure inside the chamber increases and closes the check ball under the reservoir The second check ball now opens allowing the oil to flow into the chamber under the cylinder ram 3 4297 424 The force needed to extend the cylinder ram is dependent on the amount of weight on the ram A five pound weight requires five pounds of force to lift Because the size area of the cylinder can not be changed adding more weight to the cylinder requires a higher pressure to achieve movement When the pump reaches the end of its stroke pressure under the pump and cylinder equalizes allowing the check valve to close and trapping the oil under the cylinder 3 4297 425 Productivity Series 18 UNDERSTANDING CIRCUITS HYDRAULICS Building A Basic Circuit Cont d This cycle is repeated until the cylinder ram is fully extended Notice in the simplified system the ram can not be let down To accomplish this we need to add a second valve under the cylinder This valve should not open unless the pressure capacity of the system is met or it is manually opened to let the cylinder ram down A return line will direct the oil from the cylinder back to the reservoir 3 4297 426 Building A Lift System Let
20. hoses lines kinked Are there any signs of leakage Inspect the drive for the system Does the input drive line look normal Are there signs of slippage in the system Inspect the output drive Does everything seem secure Are the drive keys in place Can you push the unit without activating the push valve Step 4 Operate the Machine to Verify If the machine still operates use the detailed problem description to verify what the operator experienced Use circumstances similar to those provided in the problem description to reproduce the problem While operating the unit note anything that may affect the hydraulic systems operation How well does the engine run Do the brakes work properly Are there any belts slipping Do the controls work smoothly Does the system operate properly in one direction and not the other Be sure to record all your observations 28 PROBLEM SOLVING Step 5 List The Possible Causes Make a list of the possible causes for this problem Use your notes to support your conclusions Which causes best match the description of the problem Which causes can be easily verified Step 6 Test Possible Causes Using the technical information and the proper test equipment test the possible causes to verify your conclusions Start with the items on your list which are the easiest to check If itis not be possible to pinpoint the problem to one component an internal inspection will
21. is responsible for protecting the system from high pressure Productivity Series 22 SPECIFICATIONS HYDRAULICS We use several different hydraulic systems across our product line All of these systems are made from the basic components described earlier and operate by using the fundamental principles of hydraulics Eaton Model 7 This hydrostatic transmission has a variable radial ball piston pump and fixed displacement radial ball motor Maximum pump output is 0 465 cu in 7 62 cc per revolution The motor output is 0 767 cu in 12 57 cc per revolution It does not use a charge pump A fine screen at the bottom of the reservoir provides for filtration of incoming oil This unit must be coupled to a final drive to provide power to the drive wheels 1 1311 2 Eaton Model 11 The Eaton 11 is similar to the model 7 but is considerably larger and uses an auxiliary charge pump The pump displaces a maximum of 1 15 cu in 18 85 cc per revolution and the motor has a 2 09 cu in 34 25 cc displacement per revolution The charge pump supplies a maximum flow of 1 5 gpm 5 7 l min 0 10 cu in per revolution 1 6 cc rev and can provide power for a hydraulic attachment lift This system is used with a separate filter and reservoir Again this unit must be coupled to a final drive to power the drive wheels 1 1311 4 23 Productivity Series HYDRAULICS SPECIFICATIONS T 1311 3 1
22. ll give you the basic fundamentals needed to become an expert in hydraulics HYDRAULICS f FILTER TRANSAXLE SUMP 1 M M P l CHARGE PRESSURE i 1 RELIEF VALVE i i MOTION FORWARD REVERSE CHECK VALVES SHAFT L I RADIAL BALL PISTON ley HYDRAULIC MOTOR OUTPUT FIXED DISPLACEMENT SHAFT RADIAL BALL PISTON HYDRAULIC PUMP VARIABLE DISPLACEMENT Ea ACCELERATION VALVES HYDRAULIC PUMP HYDRAULIC LIFT CONTROL VALVE WITH 700 PSI RELIEF VALVE TRANSMISSION CHARGE PRESSURE 30 80 PS IMPLEMENT LIFT SYSTEM PRESSURE 700 PSI Review SECTION Productivity Series HYDRAULICS INTRODUCTION f 1 1311 9 Hydrostatic Drive Gear Drive Pressure vs Load Load Productivity Series The Basic Principle of Hydraulics Hydraulics refer to the use of liquids to transmit energy In hydrostatic systems mechanical energy from an external source is converted into hydraulic pressure The pressure is then transferred through a circuit and re converted into mechanical energy In our products the mechanical energy is supplied by an engine and the liquid used to transfer energy is oil Benefits of Hydraulics Let s look at some of the benefits of using hydraulics to transmit power as compared to a mechanical system 6 Hydrostatic transmissions provide for infinite variation of output speed A mechanical transmission is limited by the number of gear ratios it has
23. n internal spring assists in returning the control arm to neutral A dampening piston is used on the motion control input arm to smooth directional changes 1 1311 7 Productivity Series 26 PROBLEM SOLVING 27 Using a systematic approach makes hydraulic troubleshooting easy By following a process which narrows down the possible causes a problem can be pinpointed and confirmed Step 1 Ask the Operator Step 2 Study the Available Information Step 3 Inspect the Machine Step 4 Operate the Machine to Verify Problem Step 5 List the Possible Causes Step 6 Test Possible Causes Step 1 Ask The Operator A detailed problem description is a valuable diagnostic tool during troubleshooting Has there been oil loss from the system What type of terrain slope was the product used on How was the unit being used How warm was the fluid What type of maintenance has been performed Did anything unusual happen before the problem occurred Answers to these questions should be recorded on the work order Step 2 Study The Available Information Review the technical information which applies to the hydraulic system you are working with Flow diagrams will show which types of components are involved in the system Can the problem be related to a particular circuit or part of a circuit Does the problem seem to be pressure related Does the problem seem to be related to oil flow What components are controlling the
24. ood quality pressure gauge is usually liquid filled to stabilize the needle Low pressure gauges for hydraulic testing will read from O to 1000 psi 70 3 kg sq cm A high pressure gauge normally allows for testing between 0 and 5000 psi 351 3 kg sq cm 30 TEST EQUIPMENT Flow Meter Load Valve Flow Meters are used to measure the actual flow in a circuit during operation The meter is placed inline and will indicate flow in gallons per minute gpm A Load Valve is a flow control valve which can be used during testing to simulate a load As the flow is restricted a higher load is simulated Load valves are usually used in combination with a flow meter Test Equipment Needs The type of test equipment you need depends on the type of equipment being serviced in your shop Generally test gauges can be adapted to many different systems simply by using adapter fittings Your test equipment should be capable of handling pressures greater than the pressure generated by the largest system you will need to test A liquid filled gauge capable of 1000 psi 70 3 kg sq cm will be sufficient for testing hydraulic systems on TORO Wheel Horse riding products Some systems used on TORO ProLine equipment require a flow meter capable of measuring at least 7 GPM A high pressure gauge may also be needed When performing a traction test on a ProLine 220 pressures in excess of 4000 psi 281 kg sq cm will be experienced Lo
25. revolution To change the output the speed at which the pump operates must be changed A variable displacement pump can change its output per revolution 3 4297 401 Pumps By Type l Axial Piston design pumps use a set of pistons rotating in a cylinder block The cylinder block is rotated by the input shaft The end of the pistons contact a swashplate The swashplate may be a fixed angle constant displacement or adjustable to a range of angles variable displacement As the cylinder block rotates the piston either pulled by the swashplate or pushed by spring pressure extends out of the cylinder block and draws oil into the chamber On the opposite side the swashplate forces the piston in displacing oi from the base of the cylinder block 3 4297 402 Radial Ball Piston pumps use several balls which travel through bores inside a rotor As the rotor is turned by the input shaft centrifugal force throws the balls out against a cam ring Oil from a passage in the pintle flows into the chamber behind the ball With the cam ring offset the ball is pushed back s into the bore as it rotates past the narrow side S oS CAMRING This forces oil back into a second passage in tA POSITION the pintle CAM RING The cam ring offset can be either fixed to provide a constant output or adjustable to provide variable output 3 4297 403 9 Productivity Series HYDRAULICS TERMS AND COMPONENTS An Inte
26. rnal Gear Gerotor pump uses two gears to provide a constant output of oil per revolution The inner gear is offset from the pump s center and is driven by the input shaft A larger internal toothed gear or rotor surrounds the inner gear providing a rotating mesh point to trap oil True internal gear pumps use a crescent seal which provides a sealing area between both gears Gerotor pumps utilize rounded teeth which do not require a crescent for sealing 3 4297 404 A Roller Bearing pump is variation of the internal gear pump Instead of using two gears rollers are placed between the teeth of the driven gear This also provides a constant displacement of oil 1 1311 1 External Gear pumps use two tightly meshed gears to produce a constant displacement of oil per revolution The input shaft drives one of the gears which in turn drives the second gear The opposed gear rotation draws oil from the inlet port and traps it between the gear teeth and the pump body As the teeth come together near the outlet port the area is reduced and oil is forced out of the pump 3 4297 405 Productivity Series l 10 TERMS AND COMPONENTS HYDRAULICS HYDRAULIC COMPONENTS cont d 11 A Charge Pump is a small constant displacement pump which is driven by the input shaft It provides a base circuit pressure and flow which can be used for the following functions Transferring oil from the reservoir to the hydrostatic p
27. se conditions Be sure to check for Service Bulletins which may apply to this system HYDRAULICS Example Complaint Lift system doesn t work Can not get the deck to raise Problem Description Hasn t noticed oil loss Used on fairly flat yard for mowing only Same operation if hydro cold or warm Use 5 seasons never serviced Circuit Involves Charge Pump Spool Valve Lift Cylinder Filter Lines amp Fittings Control Linkage for spool valve Productivity Series HYDRAULICS Inspection Results Oil is fairly clean no signs of water or overheating Spool valve works smooth Hydro is clean Hoses appear in good shape Does not apply unit drives great so the problem is in the lift circuit O er ting Test Results Drive operation OK Engine runs OK Lift system does not work Seems like it tries to raise deck Noisy when spool valve is off center Productivity Series PROBLEM SOLVING Step 3 Inspect The Machine Its now time to collect physical evidence Again take notes on what you see Inspect the the oil in the unit Is the oil level correct Does it look black Dirt Does it look milky Water Does it smell burnt Overheated Are there bubbles in the reservoir Air leak Inspect the outside of the hydraulic system Does the control linkage work properly Does it have full travel Is it secure Is there debris around the hydraulic components Are the
28. ual without notice Copyright All Rights Reserved 1994 The Toro Company
29. uid Some systems use the gear case as a reservoir This allows dirt and metal filings to settle out of the fluid This type of reservoir allows for more fluid capacity which in turn assists in keeping the system properly cooled Reservoirs are generally vented and should prevent dirt or water from entering the system 1 1311 18 Filter Hydraulic filters are special purpose filters which are able to entrap extremely small particles of dirt A typical hydraulic filter will trap particles as small as 25 microns or less Most engine oil filters only trap particles larger than 70 microns Hydraulic filters do not have a bypass valve like an engine oil filter When a hydraulic filter becomes clogged oil flow is reduced and erratic operation will be evident How Big Is A Micron 8 Microns 25 Microns O Red Blood Cell White Blood Cell OOo 100 Microns 70 Microns 40 Microns Grain Of Salt Human Hair Lower Limit Of Visibility 1 Micron 0 00003937 or 0 001 mm 1 1311 17 Productivity Series 8 TERMS AND COMPONENTS HYDRAULICS HYDRAULIC COMPONENTS cont d Pump Function A pump is a device that transfers fluids by either suction pressure or both A pump converts HYDRAULIC mechanical energy into hydraulic pressure and MECHANICAL PRESSURE flow Pumps can either be fixed or variable ENERGY displacement A fixed constant displacement pump HYDRAULIC transfers a set amount of fluid during each
30. ump 6 Pushing oil through a system filter Supplying oil to remote lift cylinders Valve Function Valves are used to provide control in a hydraulic system They can be used to control 6 Pressure Direction Of Flow Volume Of Flow We will first review these three functions of valves and then review some of the common types of valves you may encounter Pressure Control valves may be used to provide an upper pressure limit or to maintain a minimum pressure in a circuit For an example let s look at a lift system High pressure is generated when objects heavier than the system design are encountered or when a cylinder reaches the end of its stroke The pressure control relief valve opens when the upper pressure limit of the system is reached With the valve open a pressure escape path routes the oil back into the low pressure side of the circuit protecting the system components from damage CHARGE PLUMP 3 1811 4 3 4297 406 3 4297 407 Productivity Series AN HYDRAULICS TERMS AND COMPONENTS Directional Valves are used to control the direction or path of fluid flow in a hydraulic system This may consist of a check valve preventing backflow through a line or a spool valve diverting the fluid s path to a remote cylinder 3 4297 408 Flow Control valves are used to regulate flow into or out of a hydraulic component With a lift cylinder a flow control v
31. ure during operation while the unit is running or shortly after it has been running Avoid fires and explosions Avoid spilling fuel and never smoke while working with any type of fuel or lubricant Wipe up any spilled fuel or oil immediately Never remove the fuel cap or add fuel when the engine is running Always use approved labeled containers for storing or transporting fuel and lubricants Avoid Asphyxiation Never operate an engine in a confined area without proper ventilation Avoid injury from batteries Battery acid is poisonous and can cause burns Avoid contact with skin eyes and clothing Battery gases can explode Keep cigarettes sparks and flames away from the battery Avoid injury due to inferior parts Use only original equipment parts to ensure that important safety criteria are met Avoid injury to bystanders Always clear the area of bystanders before starting or testing powered equipment Avoid injury due to projectiles Always clear the area of sticks rocks or any other debris that could be picked up and thrown by the powered equipment Avoid modifications Never alter or modify any part unless it is a factory approved procedure Avoid unsafe operation Always test the safety interlock system after making adjustments or repairs on the machine Refer to the electrical chapter later in this manual for more information TABLE OF CONTENTS E ES INTRODUCTION E
32. w High Pressure Pressure Gauge HYDRAULICS 1 1311 16 1 1311 20 Flow Meter Load Valve ProLine 100 Series ProLine 200 Series Productivity Series HYDRAULICS REVIEW SECTION 3 1 The first step in problem solving is to A Study the available information B List the possible causes C Inspect the machine D Ask the operator E Operate the machine to verify the problem 2 Oil which looks milky is most likely contaminated with A Milk B Dirt C Water D Transmission fluid E Nothing 3 Anindicator of an overheated hydraulic system is A Burnt smelling fluid B Oilloss in the system C Loss of power as the system warms D Air bubbles in the reservoir E Black colored oil 4 When testing the possible causes of a hydraulic system problem always test the possibilities first 5 When using a load valve during testing as flow is restricted a higher is simulated 6 The test equipment used in your shop should be capable of handling the ___ generated by the largest hydraulic system you will need to test f Productivity Series 32 REVIEW SECTION ANSWERS HYDRAULICS Review Section 1 mechanical pressure pressure Hydrostatics distance 1 2 3 4 5 work 6 gallons minute T fixed constant 8 Pressure Control Direction Of Flow Volume Of Flow 9 mechanical energy 1 O single action Review Section 2 1 Both gauges will rea
33. ze the reader with basic hydraulics It starts by defining common terms and components used with hydraulics The components are then put together to show how they function in a hydraulic circuit Once you are familiar with the basics the book will review some of the systems that are used on TORO equipment A section on problem solving covers what to do when you encounter a problem Test equipment is also reviewed to ensure you can properly diagnose and repair hydraulic systems For detailed service information on a specific unit please refer to the appropriate service and repair manual This publication uses a building block approach It is necessary to understand the information in the front of the book to better understand information presented later Review sections throughout the book include questions which involve the key concepts presented If some questions are difficult to answer review the information again before proceeding Answers to the review questions are provided near the end of the book Why Should Read This Book Hydraulics make up an important and expensive part of many of our products Mis diagnosing a problem causes frustration for you and your customer not to mention unnecessary repair bills Understanding the basic principles of hydraulics and the components used in these systems will improve your ability to properly diagnose and repair hydraulic systems The information presented in this book wi
Download Pdf Manuals
Related Search