simboluri hidro

8/3/2019 simboluri hidro

1/57

GOLFTURF

Training Department

&

John Deere

Foundations

Hydraulic


2/57

Pumps

Axial Piston Pump

Gear Pump

Motors

Check Valve

Reservoirs

Conditioners

Pascals Law

Application Principles

Hydraulic Valve JIC

Build With JICs

(Left Click Selection Box)

Hydraulic Cylinder Principles

Cylinder Leakage Test

Relief Valve

Lines and Connections

Pressure Differential Relief

Hydraulic Fluid

Least Resistance

Open vs ClosedJIC


3/57

3

Liquids Have no Shape of their own


4/57

4

Liquids are

Practically Incompressible


5/57

5

Liquids under pressure follow

what path?

Path of least Resistance


6/57

6

Path of Least Resistance

10 lbs


7/57

Pascals LawPascals Law

Pressure Exerted on a Confined Fluid is

Transmitted Undiminished in All

Directions and Acts With Equal Forceon Equal Areas and at Right Angles to

Them.

7

Imperial

Metric


8/57

This slide illustrates one of the basic principles of hydraulics;

LIQUIDS TRANSMIT APPLIED PRESSURE EQUALLY IN ALL

DIRECTIONS.BUILDS:

1. When a 1 lb (.45kg) force is applied to this handle and the area of the

piston is 1sq in (.65cm2), with the confined fluid, what PSI (kpa)

pressure will be produced? (1psi (6.9kpa))

Note that this pressure is exerted in every direction.

2. With a 10 sq in (6.5cm2) piston, how much weight will this system

lift? This principle is what allows us to multiple our work efforts.

With 1 lb (.45kg) of down pressure, we are able to lift 10 lbs (4.5kg).

Pressure is caused by a resistance to flow, in this case the 10 lb(4.5kg) weight. Point out that resistance to flow is what causes

pressure. In this example, if there were a 100 lb (45kg) weight on the

right side (in place of the 10 lb (4.5kg) weight), how much pressure

would be required to lift it. (10 PSI (69kpa)).


9/57

--Hydraulics is a means of power transmission

--Oil is the most commonly used medium because it serves as a lubricant

and is practically non-compressible (it will compress approximately 1/2

of a 1 percent per 1000 PSI).

--Weight of oil varies with viscosity, but averages between 55 to 55 lbs

per cubic foot. (at 100 degrees F).

NOTE: A cubic foot of oil is 1728 Cu.In (12x12x12). A gallon is 231

Cu.In., so a Cubic Foot of oil is equivalent to 7.48 Gallons.--A liquid is pushed, NOT DRAWN, into a pump. Atmospheric pressure

equals 14.7 PSI at sea level.

--Oil takes the course (path) of least resistance.

FORMULAS;1. H.P. = GPM x Pressure x .000583 -or- H.P. = GPM x PSI / 17142. One H.P. = 33000 ft./lbs. per minute (33000 lbs raised 1 ft in 1 minute)

One H.P. = 746 Watts, One H.P. = 42.4 BTU per minute

3. Required Area of a transmission line;

Area = GPM x .3208 / velocity (ft./sec) -or- Velocity (ft./sec) = GPM / 3.117 x Area

Pascals Law, named after Blaise Pascal (French 1623-1662)

IMPERIAL


10/57

--Hydraulics is a means of transmitting power.

--Oil is the most commonly used medium because it serves as a lubricant

and is practically non-compressible (it will compress approximately 1/2

of 1 percent per 690 kpa).

--Weight of oil varies with viscosity, but averages between 23 to 25 kg

per cubic foot. (at 100 degrees F).

NOTE: A cubic foot of oil is 1728 Cu.In (12x12x12). A gallon is 231

Cu.In., so a Cubic Foot of oil is equivalent to 7.48 Gallons.--Liquid is pushed (by Atmospheric Pressure), NOT DRAWN, into a

pump. Atmospheric pressure equals 14.7 PSI at sea level.

--Oil takes the path (line) of least resistance.

FORMULAS;1. H.P. = GPM x Pressure x .000583 -or- H.P. = GPM x PSI / 17142. One H.P. = 33000 ft./lbs. per minute (33000 lbs raised 1 ft in 1 minute)

One H.P. = 746 Watts, One H.P. = 42.4 BTU per minute

3. Required Area of a transmission line;

Area = GPM x .3208 / velocity (ft./sec) -or- Velocity (ft./sec) = GPM / 3.117 x Area

Pascals Law, named after Blaise Pascal (French 1623-1662)

METRIC


11/57

Application PrinciplesApplication Principles1 lb (.45kg)

Force

1 sq in

(.65cm2)

Piston Area

1 psi

(6.9kpa)

10 sq in(6.5cm2)

Piston Area

10 lbs (4.5kg)

11


12/57

THE TWO MAIN TYPES OF PUMPS:

1. With a positive displacement pump, with each revolution, a specificamount of fluid is pumped somewhere.

2. The non-positive pump can rotate all day and not necessarily cause

fluid to flow.

Thus the positive displacement pump is used in applications that

require higher pressures and the non-positive displacement pumps are

used in applications that require high volumes (flow rates).


13/57

Pump TypesPump Types

Positive Displacement

-With each revolution a specific

amount is pumped somewhere Low Volume, High Pressure

Non Positive (IE: Water Pump)

High Volume, Low Pressure

13


14/57

14

JIC SymbolsJIC Symbols

Joint Industry Council

Symbolic Drawings used in Schematics

to Represent Components.


15/57

J I C Symbols

Joint Industrial Council

2139 Wisconsin Ave, NWWashington, DC 20007

This organization was founded in 1965. JIC standards replaced those

written by the Joint Industrial Conference (mostly auto manufacturing)

BUILDS1. Circle, the major components in a JIC schematic are circles. For a

pump with start with a circle.

2. Then we add an arrow head. The arrow pointing out of the circle

signifies the direction of the fluid flow. OUT, indicating a pump

3. Continue to build showing two arrows heads, meaning this pump iscapable of pumping oil in two directions

4. The arrow signifies that this pump is capable of varying the amount of

flow, so it is a variable displacement pump.


16/57

Pumps (JIC Symbols)Pumps (JIC Symbols)

Arrow

ShowingOil Flow

OUT

Constant

Displacement

Single Direction

Bi-Directional,

VariableDisplacement

16Pumps convert mechanical power into hydraulic force


17/57

Heavy Duty applications that require variable displacement

bi-directional pumps, typically use axial piston pumps.

POINT OUT THE:

1. Rotating group

2. Swash plate3. Pistons


18/57

Axial Piston PumpAxial Piston Pump

Neutral Position

Vertical Swashplate

Rotating Group

Typically 9 Pistons

Piston

Swash

Plate 18

Piston

Piston

Engine Shaft Pumps

Pressure Oil

Each Piston


19/57

SWASHPLATE ANGLE, FORWARD POSITION:

1. As the hydro linkage is slowly moved forward (swashplate anglechanges) the vehicle starts to move forward.

2. The movement of the swashplate controls the direction of the motor

rotation.

3. When the swashplate is moved further forward (swashplate angle

increases), the piston assemblies start to travel further, generating

more flow, more oil is being pumped and the speed of the

vehicle is increased.

4. Flow rate is determined by length and frequency of strokes.

When full swashplate travel is reached (maximum swashplateangle), the maximum volume of oil is being discharged from the

pump, then the speed of the motors are at maximum.


20/57


Forward Position

Angled Swashplate

Rotating Group

Typically 9 Pistons 20

Pressure

Charge Oil


21/57


Reverse Position

Angled Swashplate

Rotating Group

Typically 9 Pistons 21

Charge

Pressure


22/57

Before going back into JIC symbols, lets show another very popular

type of pump or motor.

1. What clues might we have to determine whether this device is a

pump or a motor?

NOTE: Typically, a pump will have a larger INLET opening.

2. If this were a Pump and with the pump turning in the direction

illustrated by the arrows, which side is the inlet and which side is

the outlet?

Build shows inlet and outlet.


23/57

In Out

Gear Pump

or Motor

Gear Pump

or Motor

23


24/57

BUILDS:

1. Circle; as mentioned some of the major components in the hydraulicschematic are shown as circles.

2. Add an arrow head, but note how this arrow head differs from the

pump shown earlier .. it points IN.

3. Second circle with arrowhead.

This arrowhead comes down from the top.

Does this signify any difference? (NO).

4. Second arrowhead.

What type of motor is this? (bi-directional)


25/57

Motors (JIC Symbols)Motors (JIC Symbols)

Single Direction

Arrow Showing

Oil Flow IN

Bi-Directional

25Motors converts hydraulic force into mechanical power


26/57

ReservoirsReservoirs

1. Vented 2. Pressurized

3. Return Above

Fluid Level

4. Return Below

Fluid Level26


27/57

Lines and ConnectionsLines and Connections

27

Working Line (Main)

Pilot Control Line

Drain Line

Flow Direction

Crossing Lines

or

Connecting Lines

Flexible Line


28/57

Check ValveCheck Valve

28

Checked Flow Free Flow

Pilot Operated

Spring Assisted


29/57

29

Relief Valves

Protects the Pump and Lines

from excessive pressure

Returns fluid back to the reservoir


30/57

Relief ValveRelief Valve

30

Supply

Pilot supply

Return to

Reservoir


31/57

Pressure Differential ValvePressure Differential Valve

31

Supply

Senses the DIFFERENCE in Pressure


32/57

Manual On/Off ValveManual On/Off Valve

32


33/57

Fluid ConditionersFluid Conditioners

Filter

Oil Cooler33


34/57

34

FiltersFilters

Micron

1 Millionthof a Meter or

1 Thousandth

of a Millimeter

Internal Filter

Bypass Valve

(Optional)


35/57

35

Types of Hydraulic Systems

Open Center

Closed Center

The control valve that regulates the flow from the pump

determines if system is open or closed.

Do not confuse Hydraulics with the Closed Loop of the

Power Train. (Hydro)


36/57

36

Hydraulic Valve JICHydraulic Valve JIC

Trapped Oil

Closed Center HydraulicsOpen Center

Flow in Neutral


37/57

OPEN CENTER VALVE:

1. Hydraulic flow continually moves through the system.

2. The hydraulic pump is constantly pumping fluid.

3. The control valve is open to return in neutral to allow

the fluid to circulate.


38/57

Extend 38



39/57

Retract 39



40/57

Neutral Again 40



41/57

Lets examine what happens when a cylinder is extended. Pressure oil is

routed to the piston end. Oil from the rod end is allowed to return to the

reservoir.


42/57

Lift CylinderLift Cylinder

Extend


43/57

When cylinders leak down over a period of time, it is commonly

believed that the cylinder piston packings (O-ring seals) are the cause

of the problem.

This IS NOT TRUE!! So where does the hydraulic oil go?


44/57


Leak Down Where Does

the Oil Go??


45/57

This illustration goes beyond the practical but makes the point. Because

of the volume of oil trapped in the cylinder, the rod CANNOT retract any

further unless the trapped oil is allowed to escape somewhere. In thiscase and always with cylinders that leak down by retracting, the control

valve is leaking allowing the oil out of the cylinder.

Remember, this rule applies only when the cylinder rod retracts (oil

leaking from the piston end to the rod end and out through the control

valve). Oil can leak from the rod side to the piston side (allowing the rod

to extend) because the rod side with less volume of oil can leak into the

piston side with a greater area.


46/57


Is it Possible forThis Rod to Retract

Even With

the Piston

Removed??


47/57

Cylinder Hose FailuresCylinder Hose Failures

Effects On LinePressure When a

Cylinder Piston

Packing is

Leaking

3 Diameter Piston

1.5 x 1.5 x 3.1416 = 7.07 sq.in.

Results in 2122 PSI

1.5 Diameter Rod

.75 x .75 x 3.1416 = 1.77 sq.in.

Results in 8475 PSI

15000 lbs

of Down

Force


48/57

To test a cylinder for internal leakage (past the piston seals), remove the

cylinder pin from the rod (what ever the cylinder works on will have to

be supported). Either extend or retract the rod completely. Then removethe oil line closest to the cylinders internal piston. Connect a hydraulic

hose to the cylinder where the line was removed. Place the other end of

the hydraulic hose in a clean bucket. Pressurize the opposite side of the

cylinder with hydraulic oil. Measure leakage into the bucket. If

excessive leakage is observed into the bucket, replace cylinder piston

seals.

NOTE: On some systems, such as the John Deere light weight fairway

mowers, the line returning the lift valve will need to be capped to preventreturn oil from flowing out the line.


49/57

Retract49

Hydraulic Cylinder

Leakage Test

Hydraulic Cylinder

Leakage Test

Depending on the

System, You May

Have to Cap This Line

To Prevent ReturnOil From Leaking Out

JIC S b lJIC S b l


50/57

50


PMWould This Hydraulic

Drive System Work?

Hydraulic Drive Does NOT

Provide Dynamic Braking

Common

Reservoir

Common

Reservoir

Build the System

Yes, In one direction

JIC S b lJIC S b l


51/57

51


PM

Closed Loop Hydrostatic Transmission

Hill Simulation

JIC S b lJIC S b l


52/57

52


PM

Closed Loop Hydrostatic Transmission

Hill Simulation

JIC S b lJIC S b l Oil il


53/57

53


PM

Oil Cooler

Build the System

CommonReservoir

Common

Reservoir

Oil Filter

Inlet

Check

Inlet

Check


54/57

Both the Oil Cooler Bypass and Oil Filter Bypass are Differential Relief

Valves which have the capability of comparing pressures on the inlet

side and the pressure on the outlet side;

On the 3365 WARM, these reliefs open:

1. Oil cooler bypass will open with a differential of 80-130 PSI

2. Filter bypass will open with a differential of 20-30 PSI

Leak off lines are NOT shown, but are required to provide;1. Lubrication

2. Cooling

3. Cleaning

JIC S b lJIC S b l Oil Fil


55/57

55


Build the System

PM

Oil Cooler

Oil Filter

ChargeRelief

Valve

Oil CoolerBypassValve

Filter

BypassValve


56/57

This slide shows normal oil flow;

1. Hydro turns providing oil flow to motors.

2. Motors turn, some oil is lost to case drain

3. Charge pump provides oil flow through;

Cooler

Filter

Inlet Check Valves

JIC S b lJIC S b l Oil Filt


57/57

57


Hydrostatic

Transmission

C t

Oil Cooler

Oil Filter

PM

ChargeRelief

Valve

Oil CoolerBypassValve

Filter

BypassValve

simboluri hidro

Documents