Basic Hydraulic

1

Basic Hydraulic

Pumps

Axial Piston Pump

Gear Pump

Motors

Check Valve

Reservoirs

Conditioners

Pascal’s Law

Application Principles

Hydraulic Valve JIC

Build With JIC’s

Hydraulic Cylinder Principles

Cylinder Leakage Test

Relief Valve

Lines and Connections

Pressure Differential Relief

Hydraulic Fluid

Least Resistance

Open vs ClosedJIC

3

Liquids Have no Shape of their own

4

Liquids are Practically Incompressible

5

Liquids under pressure follow what path?

Path of least Resistance

6

Path of Least Resistance

10 lbs

Pascal’s LawPascal’s Law

Pressure Exerted on a Confined Fluid is Transmitted Undiminished in All Directions and Acts With Equal Force on Equal Areas and at Right Angles to Them.

7

Imperial

Metric

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

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

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14

JIC SymbolsJIC Symbols

Joint Industry Council

Symbolic Drawings used in Schematics to Represent Components.

Pumps (JIC Symbols)Pumps (JIC Symbols)

Arrow Showing Oil FlowOUT

Constant Displacement Single Direction

Bi-Directional, Variable Displacement

16Pumps convert mechanical power into hydraulic force

Axial Piston PumpAxial Piston Pump Neutral Position

Vertical Swashplate

Rotating GroupTypically 9 Pistons

Piston

Swash Plate

18

Piston

Piston

Engine Shaft Pumps

Pressure Oil Each Piston

Axial Piston PumpAxial Piston Pump

Forward PositionAngled Swashplate


20

Pressure

Charge Oil

Axial Piston PumpAxial Piston Pump

Reverse PositionAngled Swashplate


21

Charge

Pressure

In Out

Gear Pumpor MotorGear Pumpor Motor

23

Motors (JIC Symbols)Motors (JIC Symbols)

Single Direction

Arrow Showing Oil Flow IN

Bi-Directional

25Motors converts hydraulic force into mechanical power

ReservoirsReservoirs

1. Vented 2. Pressurized

3. Return Above Fluid Level

4. Return Below Fluid Level

26

Lines and ConnectionsLines and Connections

27

Working Line (Main)

Pilot Control Line

Drain Line

Flow Direction

Crossing Lines

or

Connecting Lines

Flexible Line

Check ValveCheck Valve

28

Checked Flow Free Flow

Pilot Operated

Spring Assisted

29

Relief Valves

Protects the Pump and Lines from excessive pressure

Returns fluid back to the reservoir

Relief ValveRelief Valve

30

Supply

Pilot supply

Return toReservoir

Pressure Differential ValvePressure Differential Valve

31

Supply

Senses the DIFFERENCE in Pressure

Manual On/Off ValveManual On/Off Valve

32

Fluid ConditionersFluid Conditioners

Filter

Oil Cooler 33

3434

FiltersFilters

Micron 1 Millionth

of a Meter or1 Thousandthof a Millimeter

Internal FilterBypass Valve(Optional)

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

Hydraulic Valve JICHydraulic Valve JIC

Trapped Oil

Closed Center HydraulicsOpen CenterFlow in Neutral

Extend 38


Retract 39


Neutral Again 40


42

Lift CylinderLift Cylinder

Extend

44

Lift CylinderLift Cylinder

Leak Down Where Does

the Oil Go??

46

Lift CylinderLift Cylinder Is it Possible for

This Rod to Retract Even Withthe Piston Removed??

47

Cylinder Hose FailuresCylinder Hose Failures Effects On Line

Pressure When a Cylinder Piston Packing isLeaking

3” Diameter Piston1.5 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

Retract 49

Hydraulic CylinderLeakage TestHydraulic CylinderLeakage Test

Depending on theSystem, You May

Have to Cap This LineTo Prevent Return

Oil From Leaking Out

5050


PM Would This Hydraulic Drive System Work?

Hydraulic Drive Does NOT Provide Dynamic Braking

Common Reservoir

Common Reservoir

Build the System

Yes, In one direction

5151


PM

Closed Loop Hydrostatic Transmission

Hill Simulation

5252


PM

Closed Loop Hydrostatic Transmission

Hill Simulation

5353


PM

Oil Cooler

Build the System

Common Reservoir

Common Reservoir

Oil Filter

InletCheck

InletCheck

5555


Build the System

PM

Oil Cooler

Oil Filter

Charge ReliefValve

Oil CoolerBypassValve

Filter BypassValve

5757


Hydrostatic Transmission Components

Oil Cooler

Oil Filter

PM

Charge ReliefValve

Oil CoolerBypassValve

Filter BypassValve

Basic Hydraulic

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