8/3/2019 Part 02 97-2003

1/35

CHAPTER 1

INTRODUCTION

1.1 What is a Fluid System?

1.2 Hydraulic Systems

1.3 Typical Hydraulic Circuit

1

8/3/2019 Part 02 97-2003

2/35

CHAPTER 1 : INTRODUCTION

1.1 What is a Fluid Power System?

A Fluid Power System works on the principle of transmission of energy from the fluid to cause mechanical

motion in a required direction.

Any media (liquid or gas) that flows naturally or can be forced to flow could be used to transmit energy in

a fluid power system. Hydraulics implies a circuit using mineral oil. The other common fluid in fluid power

circuits is compressed air called Pneumatics. As indicated in Figure 2, atmospheric air -- compressed 7

to 10 times may also be used.

Fig. 1: Basic hydraulic power unit.

Fig. 2: Basic pneumatic power arrangement.

2

8/3/2019 Part 02 97-2003

3/35

Fluid power cylinders and motors are compact and have high energy potential. They fit in small spaces

and do not clutter the machine; have infinitely variable speed, and often replace mechanical linkages at a

much lower cost. With good circuit design, the power source, valves, and actuators will run with little

maintenance for extended times. However, some applications need the rigidity of liquids so it might seem

necessary to use hydraulics in these cases even with low power needs.

1.2 Hydraulic systems

A hydraulic system circulates the same fluid repeatedly from a fixed tank that is part of the primary

system. The fluid is an almost non-compressible liquid such as a Hydraulic Oil, so the actuators it

drives can be controlled to very accurate positions and speeds. Most hydraulic systems use mineral oil for

the operating media but other fluids such as water, ethylene glycol, or synthetic types are not uncommon.

Hydraulic systems usually have a dedicated power unit for each machine comprising of a Hydraulic

Motor and A Hydraulic Pump.

1.3 Typical hydraulic circuit

A typical Hydraulic Circuit Diagram consists of a number of components arranged together so as to

produce a systematic hydraulic system and get the desired pressure. The Hydraulic Circuit shown below

is the Primary Circuit of a Hydraulic Toe Lasting M/c which is the analyzed subject of the report. This

diagram consists of only the prime components that bring the Hydraulic Oil into working. The Oil is first

transferred by a Hyd. Pump connected to a Hydraulic Motor. The Pump receives its supply of oil from the

Accumulator which is a pressurized storage tank for Hyd. Oil. The Check Valves ensure that the Oil flows

only in the desired direction, in case of unidirectional flow.

3

8/3/2019 Part 02 97-2003

4/35

Fig 3 : Typical Hydraulic Circuit Diagram

CHAPTER 2 : COMPONENTS OF A

HYDRAULIC SYSTEM

2.1 Hydraulic Motor

2.1.1 Gear Motors

2.2 Hydraulic Pump

2.2.1 Classification of Pumps

2.2.2 Positive displacement principle

2.2.3 Reciprocating Pumps

2.3 Hydraulic Cylinders

2.3.1 Cylinder Basics

2.3.2 Single Acting cylinders

2.3.3 Standard Constructions

2.3.4 Common Variations in Hydraulic Cylinders

2.4 Hydraulic Valves

2.4.1 Direction control valves

2.4.2 Pressure control valves

4

8/3/2019 Part 02 97-2003

5/35

2.4.3 Solenoid Valves

2.5 Accumulators

CHAPTER 2: COMPONENTS OF A HYDRAULIC SYSTEM

2.1 HYDRAULIC MOTOR

Hydraulic Motor is a vital part as it provides the required Mechanical Power and Torque to operate the

Hydraulic Pump for the supply of Hydraulic Oil to the mechanism.

Motor displacement refers to the volume of fluid required to turn the motor output shaft through one

revolution. The most common units of motor displacement are in m

3

or cm

3

per revolution.

Torque output is expressed in inch-pounds or foot-pounds, and is a function of system pressure and

motor displacement. Motor torque ratings usually are given for a specific pressure drop across the motor.

Theoretical figures indicate the torque available at the motor shaft assuming no mechanical losses.

Breakaway torque is the torque required to get a stationary load turning. More torque is required to start

a load moving than to keep it moving.

Running torque can refer to a motor's load or to the motor. When it refers to a load, it indicates the

torque required to keep the load turning. When it refers to the motor, running torque indicates the actual

torque which a motor can develop to keep a load turning. Running torque considers a motor's inefficiency

and is a percentage of its theoretical torque. The running torque of common gear, vane, and piston

motors is approximately 90% of theoretical.

Starting torque refers to the capacity of a hydraulic motor to start a load. It indicates the amount of

torque which a motor can develop to start a load turning. In some cases, this is considerably less than the

motor's running torque. Starting torque also can be expressed as a percentage of theoretical torque.

Starting torque for common gear, vane, and piston motors ranges between 70% and 80% of theoretical.

Mechanical efficiency is the ratio of actual torque delivered to theoretical torque.

Torque ripple is the difference between minimum and maximum torque delivered at a given pressure

during one revolution of the motor.

Motor speed is a function of motor displacement and the volume of fluid delivered to the motor.

5

8/3/2019 Part 02 97-2003

6/35

Maximum motor speed is the speed at a specific inlet pressure which the motor can sustain for a limited

time without damage.

Minimum motor speed is the slowest, continuous, uninterrupted rotational speed available from the

motor output shaft.

Slippage is the leakage through the motor or fluid that passes through the motor without performing

work.

2.1.1 GEAR MOTORS

External gear motors, consist of a pair of matched gears enclosed in a single housing. Both gears have

the same tooth form and are driven by pressure fluid. One gear is connected to an output shaft; the other

is an idler. Pressure fluid enters the housing at a point where the gears mesh. It forces the gears to rotate,

and follows the path of least resistance around the periphery of the housing. The fluid exits at low

pressure at the opposite side of the motor.

Close tolerances between gears and housing help control fluid leakage and increase volumetric

efficiency. Wear plates on the sides of the gears keep the gears from moving axially and help control

leakage.

Internal gear motors fall into two categories. A direct-drive generator motor consists of an inner-outer

gear set and an output shaft. The inner gear has one less tooth than the outer. The shape of the teeth is

such that all teeth of the inner gear are in contact with some portion of the outer gear at all times. When

pressure fluid is introduced into the motor both gears rotate. The motor housing has integral kidney-

shaped inlet and outlet ports.

2.2 HYDRAULIC PUMPS

2.2.1 Classification of Pumps

All pumps may be classified as either positive-displacement or non-positive-displacement. Most pumps

used in hydraulic systems are positive-displacement.

A non-positive-displacement pump produces a continuous flow. However, because it does not provide

a positive internal seal against slippage, its output varies considerably as pressure varies. Centrifugal andpropeller pumps are examples of non-positive-displacement pumps.

If the output port of a non-positive-displacement pump were blocked off, the pressure would rise, and

output would decrease to zero. Although the pumping element would continue moving, flow would stop

because of slippage inside the pump.

6

8/3/2019 Part 02 97-2003

7/35

In a positive-displacement pump, slippage is negligible compared to the pump's volumetric output flow.

If the output port were plugged, pressure would increase instantaneously to the point that the pump's

pumping element or its case would fail (probably explode, if the drive shaft did not break first), or the

pump's prime mover would stall.

2.2.2 Positive Displacement Principle

A positive-displacement pump is one that displaces the same amount of liquid for each rotating cycle of

the pumping element. Constant delivery during each cycle is possible because of the close-tolerance fit

between the pumping element and the pump case. That is, the amount of liquid that slips past the

pumping element in a positive-displacement pump is minimal and negligible compared to the theoretical

maximum possible delivery. The delivery per cycle remains almost constant, regardless of changes in

pressure against which the pump is working.

Positive-displacement pumps can be of either fixed or variable displacement. The output of a fixed

displacement pump remains constant during each pumping cycle and at a given pump speed. The output

of a variable displacement pump can be changed by altering the geometry of the displacement chamber.

2.2.3 RECIPROCATING PUMPS

The positive-displacement principle is well illustrated in the reciprocating-type pump, the most elementary

positive-displacement pump. As the piston extends, the partial vacuum created in the pump chamber

draws liquid from the reservoir through the inlet check valve into the chamber. The partial vacuum helps

seat firmly the outlet check valve. The volume of liquid drawn into the chamber is known because of the

geometry of the pump case.

As the piston retracts, the inlet check valve reseats, closing the valve, and the force of the piston unseats

the outlet check valve, forcing liquid out of the pump and into the system. The same amount of liquid is

forced out of the pump during each reciprocating cycle.

All positive-displacement pumps deliver the same volume of liquid each cycle (regardless of whether they

are reciprocating or rotating). It is a physical characteristic of the pump and does not depend on driving

speed. However, the faster a pump is driven, the more total volume of liquid it will deliver.

2.3 HYDRAULIC CYLINDERS

2.3.1 Cylinder Basics

The most common cylinder configuration is double acting. Routing pressurized fluid into the rod end of a

double-acting cylinder causes the piston rod to retract. Conversely, routing pressurized fluid into the cap

7

8/3/2019 Part 02 97-2003

8/35

end causes the rod to extend. Simultaneously, fluid on the opposite side of the piston flows back into the

hydraulic reservoir.

Because the area of the rod-end piston face is smaller than the cap-end area, extension force is greater

than retraction force (assuming equal fluid pressures). Because total cylinder volume is less with the

cylinder fully retracted (because of rod volume) than when the cylinder is fully extended, a cylinder

retracts faster than it extends (assuming equal flow rates).

2.3.2 Single-acting cylinders, accept pressurized fluid on only one side of the piston; volume on the

other side of the piston is vented to atmosphere or returns to tank. Depending on whether it is routed to

the cap end or rod end, the pressurized fluid may extend or retract the cylinder, respectively. In either

case, force generated by gravity or a spring returns the piston rod to its original state.

The most common type of single-acting cylinder uses a return spring. In this version, pressurized fluid

enters the cap end of the cylinder to extend the piston rod. When fluid is allowed to flow out of the cap

end, the return spring exerts force on the piston rod to retract it. Factory automation - especially material

handling - is a common application using pneumatic spring-return cylinders.

2.3.3 Standard Constructions

Construction variations for single-and double-acting cylinders are based primarily on how the two end

caps are attached to the barrel. Additional variations include wall thickness of the barrel and end caps,

and materials of construction.

Tie-rod cylinders have square or rectangular end caps secured to each end of the barrel by rods that

pass through holes in the corners of the end caps. Nuts threaded onto the end of each tie rod secure the

end caps to the barrel. Static seals in the barrel/end-cap interface prevent leakage. A number of

variations to this design exist, including use of more than four tie rods on a cylinder, or long bolts that

thread into tapped holes in one of the end caps.

The majority of cylinders for industrial, heavy-duty applications uses tie-rod construction and usually

conforms to National Fluid Power Association (NFPA) standards. These standards establish dimensional

uniformity so cylinders from multiple manufacturers can be interchanged.

2.3.4 Common variations in Hydraulic Cylinders

The implementation of Hydraulic Systems acquires many types of variations that have been developed to

meet custom requirements in different industries. Since the area and manner of Hydraulic Operation in

industries varies hence the cylinders needed to be customized as per the requirements. Some of the

variations that were used in the Hydraulic System are as follows.

8

8/3/2019 Part 02 97-2003

9/35

Most telescoping cylinders are single acting, although double-acting versions are available. Telescoping

cylinders contain five or more sets of tubing, or stages that nest inside one another. Each stage is

equipped with seals and bearing surfaces to act as both a cylinder barrel and piston rod. Available for

extensions exceeding 15 ft, most are used on mobile applications where available mounting space is

limited. The collapsed length of a telescoping cylinder can be as little as 15 its extended length, but the

cost is several times that of a standard cylinder that can produce equivalent force. Models are available in

which all stages extend simultaneously or where the largest stage extends first, followed by each

successively smaller stage.

2.4 HYDRAULIC VALVES

Hydraulic Valves are a vital components as they control the amount, timing and pressure which is to be

supplied under certain desired conditions.

2.4.1 Directional control valves

Directional Control valves are basically used to restrict the Direction of the Hydraulic Fluid in the system

to maintain the required pressure.

An isolation check valve between the pumps keeps the high-pressure pump from going to tank when

the low-volume pump unloads. A pilot-operated check valve in the line to the cap end of the main

cylinder traps fluid in the cylinder while the motor and rotary actuator operates.

The two primary characteristics for selecting a directional-control valve are the number of fluid ports and

the number of directional states, or positions, the valve can achieve. Valve ports provide a passageway

for fluid (air or hydraulic fluid) to flow to or from other components. The number of positions refers to the

number of distinct flow paths a valve can provide.

2.4.2 Pressure-control valves

A pressure-relief valve at the pumps automatically protects the system from overpressure. An

unloading valve dumps the high-volume pump to tank after reaching a preset pressure. A kick-down

sequence pressure-control valve forces all oil to the cylinder until it reaches a preset pressure.

Another pressure-control valve -- called a counterbalance valve -- located in the rod end line of the main

cylinder keeps it from running away when the directional control valve shifts. The counterbalance valve is

adjusted to a pressure that keeps the cylinder from extending, even when weight on its rod could cause

this to happen.

2.4.3 Solenoid Valves

9

8/3/2019 Part 02 97-2003

10/35

Solenoid Valves are widely used in most of Hydraulic Systems today. A Double Solenoid Valve uses two

solenoid springs powered with DC supply, and are primarily used for the opening and closing of the port

for the flow of hydraulic oil. A Single Solenoid Spring Return Valve uses the Solenoid to open the port and

employs the Spring to close the port.

2.5 ACCCUMALATORS

Because hydraulic oil is almost non-compressible, an accumulatorallows for storage of a volume of fluid

to perform work. The expandable gas in the accumulator pushes the oil out when external pressure tries

to drop. The accumulator in this circuit makes up for leakage in the cylinder cap-end circuit while pumpflow runs the hydraulic motor and rotary actuator.

10

8/3/2019 Part 02 97-2003

11/35

CHAPTER 3 : MATERIALS AND

METHODS

3.1 Toe Lasting Machine KD87A

3.2 Components of KD87A Toe Lasting Machine

3.2.1 Hydraulic Motor

3.2.1.1 Sizing Hydraulic Motors

11

8/3/2019 Part 02 97-2003

12/35

3.2.2 Hydraulic Pump

3.2.3 Hydraulic Valves

3.2.4 Hydraulic Cylinders

3.2.5 Hydraulic Fluids

3.2.5.1 Characteristics of HLP 68

3.2.5.2 Specifications of HLP 68

3.2.5.3 Additives used in HLP 68

12

8/3/2019 Part 02 97-2003

13/35

CHAPTER 3 : MATERIALS AND METHODS

3.1 TOE LASTING MACHINE KD87A by Kukdong Machinery Ltd. (SOUTH KOREA)

The machine and the Mechanical Apparatus used in our analysis is based on Toe Lasting Machine. The

machine is used in Shoe Manufacturing Process and is a vital part in the industry. It works on an Electro-

hydraulic System assisted by many other important components described later. The machine is suitable

for the Toe Stretching and Lasting of Leather, Polyurethane, Nylon and Canvas Shoes.

The Machine Dimension were recorded to be approximately 880mm(W)x1820mm(L)x 1600mm(H) with a

Dry Weight of about 1350 Kg. The machine allows 110 Ltrs. Of Hydraulic Oil storage which in turn

makes the Net Weight to approximate to 1460 Kg.

This machine has been designed and tested to undergo 8 hours of continuous operation time with a

Production Capacity of2500-3000 Pairs of shoes per day, under Standard Industry Conditions.

13

8/3/2019 Part 02 97-2003

14/35

Fig. 4: KD 87A Hyd. Toe Lasting Machine

A variety of components, systems and sub-systems combine to give result to the shape and operation of

the machine. The Machine operates on 415V of AC Power for the working of the Primary Circuit which

consists of a Step-down Transformer, Relays for Operating Electro-Hydraulic Valves and a Series of

Electrical Circuits that are responsible for the smooth and requisite Operation of the Machinery and its

components.

The Primary Electrical System can also be altered according to usage and custom requirements as per

the manufacturer. Also, it plays an important role by controlling the input of the Electrical Power flowing to

the Secondary Circuit that is connected to various Sub-systems of the machinery.

The Secondary Electrical Circuit consist of a critical assembly of Electrical Wires, one end of these is

connected to the Relays and components of the Primary Circuit for the Input Power delivery and the other

end is connected directly to the Electro-mechanical components in the machinery such as Valves, Limit

Switches, On-Off Switches, Indicators, Oil Level Meter and other Critical Sensors for measuring the

Performance of the Machinery for Optimization, which is the foremost requirement as per the growing

14

8/3/2019 Part 02 97-2003

15/35

need of Footwear worldwide, hence it is necessary for the Production to continue at Full Pace at all times

without any failures or rejections.

The major parts of the machine except from the Electro-Hydraulic System described later, include Toe

Band, A group of Pincers, Last Support, Heel Support, Two Electric Control Panels, Speed Control Panel

and a Limit Switch Position Control Rod. There are 9 Pincers available for holding the Leather Upper and

work independently from each other, as they have independent control units. For Intense compression of

the Toe Part of the Shoe, a Teflon Toe Band connected with a Hydraulic System is provided. The main

lasting operation of the shoe is done by a component call Wiper Plates, which swiftly slide beneath the

surface of the Upper Part and provide the required shape to the shoe from the Toe Part. The shape to be

followed by the Lasting Procedure depends on the Shoe Last which is made of Teflon, though it only

provides a platform for the Upper to be molded in the required shape. The last no longer stays in

connection with the developed shoe part after it is lasted on the machine.

The lasting operation is done with the help of an adhesive injector attached under the last, which provides

the low of adhesive semi-solid form and helps in attaching the Upper more firmly to the respective Shoe

part. The Injector is generally made of Brass and Aluminum and is a critical part of the operation.

Fig. 5: Critical Parts of KD 87A

The Electrical Control panels on the Left and Right sides of the machine provide platform for operations

and the necessary information for the operator of the machine. The Controls available on the panels are

Automatic/Semi-Automatic Switch, Pincer adjustment and control Switch, Wiper Plate control Switch, Toe

Band control switch, Pressure Gauges, Motor On/Off Switch), Mains indicator Light.

15

8/3/2019 Part 02 97-2003

16/35

Fig. 6: KD 87A Pressure Gauges

The whole mechanical operation that results in Shoe Manufacturing Process is controlled by a Control

Foot Pedal. This pedal has controls for the activation and deactivation of the Hydraulic Systems in the

machine. The activation of the hydraulic system occurs in three steps which can be automated to occur in

two steps as per the production requirement. The deactivation however, occurs in a single step and the

pressure is relieved from the valves and cylinders to bring the components to initial position.

Fig. 7: Upper before lasting operation

16

8/3/2019 Part 02 97-2003

17/35

Fig. 8: Upper after Lasting Operation

The whole lasting operation is performed by the operation of all the components as shown in Fig. 6, along

with the cylinders and valves they are connected to. As the machine is operated after giving electrical

supply to the Hydraulic Motor, the control pedal operates the machine in three steps, when arranged in

the semi-automatic mode. After the upper and the last are kept in position, the first stroke on the pedal

brings the top 3 pincers in operation and they hold the upper in place for the next step. On pressing the

pedal second time, the rest of the 6 side pincers hold the upper more firmly, the last support moves above

and tightens the upper even more. When these two steps are executed properly, the third stroke on the

pedal starts the lasting operation. In this step, the toe band, heel support, head hammer and the wiper

plate come in operation serial wise and complete the lasting operation. After this is done, the pedal is

pressed once again to release all the components in one stroke.

3.2 COMPONENTS OF KD87A TOE LASTING MACHINE

3.2.1 HYDRAULIC MOTOR

The Hydraulic Motor used in the Toe Lasting M/c is a three phase induction motor with Internal

Gearing. The motor operates at a supply voltage of415 Volts, has a Power Rating of 3 Horsepower

and current rating of 6.5 Amperes. This provides adequate torque of 131 lb-in to the pump. The motor

is Copper wound and has an output shaft for supplying mechanical power and torque to the hydraulic

pump used. The speed of the motor cannot be varied; hence it remains fixed at 1440rpm.

All types of hydraulic motors have these common design features: a driving surface area subject to

pressure differential; a way of timing the porting of pressure fluid to the pressure surface to achieve

continuous rotation; and a mechanical connection between the surface area and an output shaft.

17

8/3/2019 Part 02 97-2003

18/35

Fig. 9: KD 87A Hydraulic Motor

3.2.1.1 SIZING HYDRAULIC MOTORS

As an example of how to calculate hydraulic motor size to match an application, we consider the followingspecifications of the Hydraulic Motor in KD 87A: It has a motor power of3 hp and rotates at 1440 rpm;

the supply pressure is 40 psi and the excess return pressure is 5 psi, pressure differential is 35 psi.

The theoretical torque required is calculated from:

T = (63000 x horsepower)/N

Hence for KD 87A Hydraulic Motor

T = (63000 x 3)/1440 = 131.25 lb-in

Where,

T is torque, lb-in., and

N is speed, rpm.

Motor/Pump displacement is calculated as:

18

8/3/2019 Part 02 97-2003

19/35

D = 2 T PM

For KD 87A Hydraulic Motor

D = (2x3.1416x131.25)/(35x80) = 0.294525 in3/rev

Where:

D is displacement, in.3/rev

P is pressure differential, and

M is mechanical efficiency, %.

Mechanical efficiency is 80%

Calculating the required flow:

Q = DN/2.31V,

For KD 87A Hydraulic Motor

Q = (0.294525x1440)/ (2.31x85) = 2.16 gpm

V, Volumetric Efficiency is 85%

Pressure in these equations is the difference between inlet and outlet pressure. Thus, any pressure at the

outlet port reduces torque output of a fluid motor.

The efficiency factor for most motors will be fairly constant when operating from half- to full-rated

pressure, and over the middle portion of the rated speed range. As speed nears either extreme, efficiency

decreases.

Lower operating pressures result in lower overall efficiencies because of fixed internal rotating losses that

are characteristic of any fluid motor. Reducing displacement from maximum in variable-displacement

motors also reduces the overall efficiency.

3.2.2 HYDRAULIC PUMP

The pump used in the machine is a Reciprocating Hydraulic Pump and obtains its input mechanical

power from the Induction Motor connected before it through a shaft. The pump operates at around 1600

rpm and generates a maximum pressure of40 psi. The pump operates under ideal conditions of normal

industry temperature of40-60 degrees. As the pump is reciprocating, it does not transfer radial motion

to the Hydraulic Oil, rather it only provides Linear Motion due to which the pressure received is large,

19

8/3/2019 Part 02 97-2003

20/35

but only applicable for short distances, as without rotation, friction in the hoses inhibits the flow

of the Oil.

Fig. 10: Hydraulic Pump for KD 87A

When a hydraulic pump operates, it performs two functions. First, its mechanical action creates a vacuumat the pump inlet which allows atmospheric pressure to force liquid from the reservoir into the inlet line to

the pump. Second, its mechanical action delivers this liquid to the pump outlet and forces it into the

hydraulic system.

A pump produces liquid movement or flow: it does not generate pressure. It produces the flow

necessary for the development of pressure which is a function of resistance to fluid flow in the system.

3.2.3 HYDRAULIC CYLINDERS

A Hydraulic Cylinder is one of the simplest part of the cylinder, but also it lays great importance as it

completes the final execution of the Hydraulic operation. The Hydraulic Cylinders used in the machine are

varied in accordance to their requirement; there are Double-acting Cylinders, Single-acting Spring return

Cylinders and Telescopic Cylinders. The construction, design, principle and the working of these

Hydraulic Cylinders is described in the following paragraphs.

20

8/3/2019 Part 02 97-2003

21/35

The different arrangements for hydraulic cylinders used are:

09 Cylinders for Pincer Movement

02 Cylinders for Pincer Assembly movement

01 Cylinder for Head Hammer Stroke with bore diameter of 45mm and Linear displacement of

37.5mm

01 Cylinder for Bed Movement Toe Band Operation with bore diameter of 30mm and Linear

displacement of 85mm

01 Cylinder for Heel Pressing with bore diameter of 70mm and Linear Displacement of 115mm

01 Cylinder for Last Support Attachment

01 Cylinder for Wiper Plate Operation

Fig. 11: Main Cylinder with Limit Switches

3.2.4 HYDRAULIC VALVES

21

8/3/2019 Part 02 97-2003

22/35

There are in total 27 valves in the Hydraulic manifold. These valves are employed to regulate appropriate

pressure in each of the hydraulic cylinders as per the requirement.

Pressure Release Valve 01 No.

Pressure release valve is connected at the first distribution point of the hydraulic fluid and has a

function of sending the excess oil back into the hydraulic oil tank, such that the exact pressure

required is delivered.

Pilot Valves 03 Nos.

Pilot vales are connected at the main cylinder terminals so as to boost the pressure input in these

terminals to improve efficiency and the load applied by the cylinder.

Solenoid Valves 23 Nos.

Solenoid Valves are special kind of valves that employ a solenoid coil to turn Electrical Energy

into Mechanical Energy, so as to operate the cams that allow the flow of oil into the cylinders.

These Solenoid Valves function through separate relays connect to each of them for appropriate

supply of current.

22

8/3/2019 Part 02 97-2003

23/35

Fig. 12: Solenoid Valves

3.2.5 HYDRAULIC FLUIDS

Hydraulic Oil Used:

The Hydraulic Oil used in the machinery is HLP 68 which is compliant with DIN 51542 annexure 2 (DIN

Deutsch Institute fur Normang i.e. German Institute of Standardization).

H Hydraulic Oil

L with additives to protect against corrosion

P with additives to increase overall load carrying capacity

3.2.5.1 Characteristics of HLP 68:

High Pressure Susceptibility

23

8/3/2019 Part 02 97-2003

24/35

High Air and Water separating ability

Neutral towards Sealing Materials

Very Good and Stable Viscosity-Temperature Behavior

Corrosion Protection

3.2.5.2 Specifications for HLP 68:

Specific weight at 15oC : 885 kg/m3

Viscosity at 40oC : 68 cSt (Centistokes)

Viscosity at 100oC : 8.75 cSt

Flash Point : 230oC

Pour Point : 24oC

Range of Viscosity at 680C : 61.2 cSt to 74.8 cSt

FZG Test Rating : Level 12

FZG (stands for Forschungsstelle fur Zahnrader und Getriebebau i.e. Technical Institute

for Study of Gear and Drive Mechanism) Test evaluates a fluids lubricating and wear

protection properties at the interface of a loaded set of gears. During the test, the gears

are rotated through a torsion coupling that is set to known load conditions and rotated by

a motor with variable speed control. The temperature of the oil is maintained by heating

and cooling elements.

TAN value : 0.2 mg KOH/gm

TAN (stands for Total Acidic Number) is the amount of milligrams of KOH i.e. Potassium

Hydroxide, needed to neutralize the acid present in the oil. Hence, TAN value indicates

the corrosion resistance of the oil. It can be obtained by Potentiometric Titration OR by

Color Indication Titration.

3.2.5.3 Additives used in HLP 68:

24

8/3/2019 Part 02 97-2003

25/35

However, there are many additives employed to provide the required characteristics in Hydraulic oils but

the major additives are as follows:

Chromate or Nitrate: Prevents the phenomenon of Oxidation by forming a layer over the

surrounding metal tank.

Molybdenum Disulphide: Acts as a friction modifier and reduces the overall friction

acting in the system to improve efficiency.

Nonylated Diphenylamine: Acts as an Anti-Oxidant and prevents further oxidation in the

system.

CHAPTER 04 : HYDRAULIC MODEL

4.1 Hydraulic Model Details

4.2 Hydraulic Model Operation

25

8/3/2019 Part 02 97-2003

26/35

CHAPTER 4 : HYDRAULIC MODEL

4.1 HYDRAULIC MODEL DETAILS

The Hydraulic Model, as shown in Fig. 14, shows the basic operation of a Hydraulic System with the

primary components. The project has been developed so as to miniaturize the operation of each concept.

The model constructed employs a fountain pump for pumping water. The Pump is connected to a series

of components and valves in order to maintain pressure.

26

8/3/2019 Part 02 97-2003

27/35

Fig. 13: Hydraulic Model

The pump, as shown in Fig. 15, has a capacity of pumping 3500 Liters of Fluid per hour, and can

provide flow at a vertical head of 10 feet. The pump provides fluid pressure of 5 psi approximately. It

operates on 220 V/50 Hz supply and has a power rating of40 Watts.

27

8/3/2019 Part 02 97-2003

28/35

Fig. 14: Fountain Pump used as Hydraulic Pump

4.2 HYDRAULIC MODEL OPERATION

As the pump only allows water to flow and does not generate pressure for hydraulic operation, the

sockets and valves are fitted accordingly to create restriction and hence generate pressure. The diameter

of the inlet of the connecting valve is 12mm approx, which has been gradually reduced to 6mm so

that the pressure remains intact.

However, the inlet and outlet was initially kept at 12mm and directly to 6mm at the outlet port, which

caused the system to reduce pressure considerably and hence desired re sults were not obtained.

Therefore, after studying the problem it was decided to reduce the outlet diameter gradually so that the

pressure is kept intact.

The valves and connectors, refer Fig. 16, in the construction use either Mild Steel or Brass as their

material. Also, the valves and connectors were fitted using Teflon tape which prevents leakage from the

valve when the system comes in operation.

28

8/3/2019 Part 02 97-2003

29/35

Fig. 15: Valve Arrangement

After receiving the delivery of pressurized fluid (water in this case), a 50 mL syringe is connected to the

system from the front side. As the water enters the syringe, the syringe piston is forced to move

backwards due to the hydraulic force of the fluid.

The hosing used to connect the system is made ofPolyurethane which provides adequate rigidity to

the walls of the pipes so as to not lose pressure in the system. The sockets and hoses used to connect

the 6mm PU hosing is used for Pneumatic Systems, but are employed here because of the fact that

hydraulic hoses for such small diameters are not available.

29

8/3/2019 Part 02 97-2003

30/35

CHAPTER 5 : RESULTS AND DISCUSSIONS

In the above report on Hydraulic Systems and Operation, emphasis has been laid on studying the

fundamentals of Basic Hydraulic Operation, on KD87 A Hydraulic Toe Lasting Machine.

The machine works on Electro-Hydraulic Systems all placed in a single manifold. The major components

involve a 3-phase Induction Motor, A Linear Hydraulic Pump, A series of solenoid, directional and

pressure relief valves which are all connected to single and double acting cylinders. The specifications

and ratings of the motor have been calculated with the help of certain formulae, which gives the effective

torque as 131.25 lb-in, Displacement as 0.294525 in3/rev with the output flow as 2.16 gpm. The

Volumetric Efficiency has been taken as 85% and Mechanical Efficiency as 80%. All these operations

combined together result in a series of operations that result in the lasting process, which is a vital part of

the Shoe Manufacturing Process.

The Basic Hydraulic Mechanism has been demonstrated by constructing a Hydraulic Model to illustrate

the steps in Hydraulic Function. The model uses a Submersible Fountain Pump connected with valves

and hoses to supply water pressure to the cylinder. The pressure output of the pump is approximately

5psi, with 40W power output, which controls the motion of the cylinder, here used as a 50mL Syringe. The

whole system operates at normal household voltage i.e. 220V/50Hz. The Brass and Mild Steel valves

connected are configured so as to maintain consistent flow of pressurized water to the syringe. When the

Pump operates, the pressurized water is passed on from the pump to the 12mm Rubber hose connected

to the valve mechanism. The valves reduce the output flow of water to 6mm with increase in velocity of

the flow and the pressure remaining constant. The valves are connected to the syringe with a

Polyurethane pipe for supply. Hence, the pressurized water pushes the syringe piston in the direction of

flow due to the developed hydraulic force. This illustrates the basic hydraulic mechanism.

30

8/3/2019 Part 02 97-2003

31/35

CHAPTER 6 : CONCLUSION

Hydraulic Systems are one of the prime components of technical industry and find application in almost

every field of engineering. This report gives us an insight to the basic function and mechanism of a

Hydraulic System along with all its components that drive the system. The main objective of the project

lies in analyzing hydraulic systems in industry environment for which a Hydraulic Toe Lasting Machine

was studied in operation under standard industry conditions.

The research also includes topics and studies related to standardization of equipments and hydraulic oils

adopted for optimization of productivity and minimizing down-time. The Hydraulic Model constructed helps

in understanding of the hydraulic mechanism at conceptual levels and also provides scope forimprovisation and involvement of modifications. The analysis helped in the designing and construction of

the hydraulics model.

31

8/3/2019 Part 02 97-2003

32/35

CHAPTER 7 : IMPLICATIONS FOR FUTURE RESEARCH

The technology consisting of Fluid Power as its basic foundation finds application in almost every field of

scientific development. Although the basic operation and mechanics for operation of Fluid Power Systems

has not changed with time, there have however been many improvisations in the techniques and resource

development that offer much higher efficiency, reliability and productivity to the mechanism.

The Fluid Power systems mainly use one or the other form of Fluid according to the operating conditions

and the requirement referring to different fields. There has been a major research and development for

the use of more reliable and environment friendly Oils for delivering fluid power. New multi-grade oils,

optimized with high-tech polymer additives and friction modifiers, are delivering promising field results,and new hydraulic fluids have been introduced by major oil companies. Research is moving ahead on duty

cycle standards for specific vehicles, and the impact that high-efficiency hydraulic fluids (HEHF) could

have on overall equipment design, particularly high-pressure and high-temperature applications such as

excavators, skid steer loaders and construction equipment.

The use of Shear Stable polymer additives increases the efficiency of the hydraulic pump by at least 10

percent and improves the overall reliability of the system. Also, systems have been modified to use oils

that are biodegradable and non-toxic. The polymer-enhanced hydraulic fluid has a thickening effect, which

causes the oil to thin out at a slower rate as the temperature increases. As a result, there is an increase in

volumetric efficiency and less internal leakage in the pumps and motors.

The motor and pump consume the maximum amount of fluid per unit time when they are initially started.

As a result, a motor and pump with displacement higher than required is employed to create the extra

starting torque needed. Therefore, with improved properties of lubricants and hydraulic fluids the

displacement of the motor and pump may be reduced without compromising the efficiency and

productivity of the system. It was recorded that under viscosity modifying additives the motor efficiency

was improved by 7 percent of earlier.

While research is ongoing in a variety of areas, field trials and a decade of laboratory testing demonstratethat shear stable multi-grade hydraulicfluids and friction modifiers improve energy efficiency in hydraulic

systems. Fluids that meet the requirements of the NFPA Energy Efficient Hydraulic Fluidclassification

system increase fuel economy and productivity while reducing CO2 emissions. And in the last year, oil

companies including Shell, ExxonMobil and Citgo have introduced new high-efficiencyhydraulic fluids, and

OEMs are beginning to specify the fluids in their products.

32

http://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.php

8/3/2019 Part 02 97-2003

33/35

Since mobilehydraulic systems generally operate in the steep portion of the volumetric efficiency curve,

increasing the viscosity of the hydraulic fluid at high temperatures improves volumetric efficiency and

reduces energy consumption. During cold temperature start-up, when the viscosity of the hydraulic fluidis

potentially very high, a low-viscosity hydraulic fluid improves mechanical and overall efficiency. Both of

these goals can be achieved through the use of a shear stable high hydraulic fluid.

Fig. 16:Efficiency-Viscosity Curve

33

http://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.phphttp://www.designnews.com/hottopic/Fluid_Power_and_Power_Transmission/index.php

8/3/2019 Part 02 97-2003

34/35

CHAPTER 8 : REFERENCES

1. FLUID POWER CIRCUITS EXPLAINED

Written by: Bud Trinkel, Certified Fluid Power Engineer

Edited by Mary Gannon and Richard Schneider, Hydraulics & Pneumatics magazine.

PRACTICAL KNOWLEDGE ABOUT HYDRAULIC AND PNEUMATIC COMPONENTS AND SYSTEMS

Written by: Bud Trinkel, Certified Fluid Power Engineer

Edited by Mary Gannon and Richard Schneider, Hydraulics & Pneumatics magazine.

2. KD87A Operation Manual provided by Kukdong Machinery Limited.

3. Internet Reference

http://www.fpweb.com/200/FPE/IndexPage.aspx

4. CONTROL SYSTEMS AND ENGINEERING by I.J. Nagrath and M. Gopal

34

http://www.fpweb.com/200/FPE/IndexPage.aspxhttp://www.fpweb.com/200/FPE/IndexPage.aspx

8/3/2019 Part 02 97-2003

35/35