power assisted gear shifting

8/9/2019 power assisted gear shifting

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ABSTRACT

This paper is based on the project “Power Assisted Gear Shifting Mechanism for

Automobiles”. This is a design, fabrication and implementation project. The project provides

solution for gear shifting for the cars. The passenger cars that now ply on the road have

transmission either of manual or automatic type of gear changing. The manual type of

transmission is preferred for the perfect performance without a loss in power but a

compromise for comfortness. In this type automatic system of power transmission there is

easiness of gear shifting but there is a definite loss of power and mileage.

The main objective of this project is to create a mechanism to reduce theinconvenience caused when changing gears in the car. The gear shifting here is by mere

pressing of feather touch buttons present on the dash board. The gear shifting is by hydraulic

force achieved by a simple modification to the gear box. The setup consists of power steering

pump, piston cylinder assembly and a set of fluid valves.

This project if implemented is a clear alternative for the Automatic transmission

because of its low cost and ease of use. Moreover the whole set up is small and requires a

very small space. This can sure be a standard fitment if proper marketing strategy is carried

out. Further, automatic clutch can be incorporated with this unit to make it fully automatic.


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HISTORY

Modern automatic transmissions can trace their origins to an early "horseless carriage"

gearbox that was developed in 1904 by the Sturtevant brothers of Boston, Massachusetts.

This unit had two forward speeds, the ratio change being brought about by flyweights that

were driven by the engine. At higher engine speeds, high gear was engaged. As the vehicle

slowed down and engine RPM decreased, the gearbox would shift back to low.

Unfortunately, the metallurgy of the time wasn't up to the task, and owing to the abruptness

of the gear change, the transmission would often fail without warning.

The next significant phase in the automatic transmission's development occurred in 1908 with

the introduction of Henry Ford's remarkable Model T. The Model T, in addition to beingcheap and reliable by the standards of the day, featured a simple, two speed plus

reverse planetary transmission whose operation was manually controlled by the driver using

pedals. The pedals actuated the transmission's friction elements (bands and clutches) to select

the desired gear. In some respects, this type of transmission was less demanding of the

driver's skills than the contemporary, unsynchronized manual transmission, but still required

that the driver know when to make a shift, as well as how to get the car off to a smooth start.

In 1934, both REO and General Motors developed semi-automatic transmissions that were

less difficult to operate than a fully manual unit. These designs, however, continued to use

a clutch to engage the engine with the transmission. The General Motors unit, dubbed the

"Automatic Safety Transmission," was notable in that it employed a power-shifting planetary

gearbox that was hydraulically controlled and was sensitive to road speed, anticipating future

development.

Parallel to the development in the 1930s of an automatically shifting gearbox was Chrysler'swork on adapting the fluid coupling to automotive use. Invented early in the 20th century, the

fluid coupling was the answer to the question of how to avoid stalling the engine when the

vehicle was stopped with the transmission in gear. Chrysler itself never used the fluid

coupling with any of its automatic transmissions, but did use it in conjunction with a hybrid

manual transmission called "Fluid Drive" (the similar Hy-Drive used a torque converter).

These developments in automatic gearbox and fluid coupling technology eventually

culminated in the introduction in 1939 of the General Motors Hydra-Matic, the world's first

mass-produced automatic transmission.

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INTRODUCTION

The paper deals with the real time project, Power Assisted Gear Shifting Mechanism

for Automobiles which was done in the academic year 2004- 2005. The paper deals with thevarious design aspects of the creation of this project. This project is aimed at giving driver the

convenience for gear shifting. The car with this project will have a series of buttons in the

format of 4 forward, a reverse and a neutral. The clutch operation may or may not be put in

the car depending on the user. Currently the project has been done for the transmission of

third and reverse gears. The whole setup which is done on experimentation purpose proves to

be a promising one. The power for gear shifting is got from hydraulic fluid. The power for

fluid is from the power steering pump. So a car with a power steering fitment can be easily

adaptable to this project. The project has been started as a concept and it requires a lot more

work to be done to put in a car.

Whenever a project is carried out there is a reason behind it. The existing cars now

pose some problems for the drivers. In the Manual Transmission cars the main problem for

the drivers is the gear shifting & In the Automatic Transmission type of cars, the gear shifting

is easy. We just have to select the drive band, which is already pre-set. This selection may be

either of lever type or a set of buttons. This is easy for the drivers as they don’t have to use

clutch during gear shift. But there is a compromise for power transmission and mileage. As

the gear selection is by a fluid, power is required to drive it, so the engine performance is

reduced. So the problem here is mileage drop, power loss and also it is costly.

The need of the hour, combining the position of both MT and AT a mechanism has to

be created for better mileage and comfortable gear shifting. This is the objective of the

project. So a car with this project provides ease of gear shift as in AT without a compromise

in box.


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PROBLEM DEFINITION

Whenever a project is carried out there is a reason behind it. The existing cars now

pose some problems for the drivers. In the Manual Transmission cars the main problem forthe drivers is the gear shifting. But the engineering concept behind this type of transmission

paves way for higher power transmission efficiency. More over the mileage of the car and life

is also more. These cars do not give much of comfort ness for the drivers in the terms of

using the gear lever and the clutch. Also it occupies a major area in the cabin resulting in the

space congestion. These are the problems in the Manual Transmission cars.

In the Automatic Transmission type of cars, the gear shifting is easy. We just have to

select the drive band, which is already pre-set. This selection may be either of lever type or a

set of buttons. This is easy for the drivers as they don’t have to use clutch during gear shift.

But there is a compromise for power transmission and mileage. As the gear selection is by a

fluid, power is required to drive it, so the engine performance is reduced. So the problem here

is mileage drop, power loss and also it is costly.

The need of the hour, combining the position of both MT and AT a mechanism has to

be created for better mileage and comfortable gear shifting. This is the objective of the

project. So a car with this project provides ease of gear shift as in AT without a compromise

in box.


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TRANSMISSION

Five-speed + reverse gearbox from the 1600 Volkswagen Golf (2009).

A machine consists of a power source and a power transmission system, which

provides controlled application of the power. Merriam-Webster defines transmission as an

assembly of parts including the speed-changing gears and the propeller shaft by which the

power is transmitted from an engine to a live axle.[1] Often transmission refers simply to

the gearbox that uses gears and gear trains to providespeed and torque conversions from a

rotating power source to another device.[2][3]

In British English, the term transmission refers to the whole drive train, including

clutch, gearbox, prop shaft (for rear-wheel drive), differential, and final drive shafts. In

American English, however, the distinction is made that a gearbox is any device which

converts speed and torque, whereas a transmission is a type of gearbox that can be “shifted”

to dynamically change the speed-torque ratio such as in a vehicle.

The most common use is in motor vehicles, where the transmission adapts the output

of the internal combustion engine to the drive wheels. Such engines need to operate at a

relatively high rotational speed, which is inappropriate for starting, stopping, and slower

travel. The transmission reduces the higher engine speed to the slower wheel speed,

increasing torque in the process. Transmissions are also used on pedal bicycles, fixed

machines, and anywhere else where rotational speed and torque needs to be adapted.

Often, a transmission will have multiple gear ratios (or simply “gears”), with the

ability to switch between them as speed varies. This switching may be done manually (by the

operator), or automatically. Directional (forward and reverse) control may also be provided.

http://en.wikipedia.org/wiki/Machine_(mechanical)http://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-1http://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-1http://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-1http://en.wikipedia.org/wiki/Gearhttp://en.wikipedia.org/wiki/Gear_trainhttp://en.wikipedia.org/wiki/Speedhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-2http://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-2http://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-2http://en.wikipedia.org/wiki/Drive_trainhttp://en.wikipedia.org/wiki/Motor_vehiclehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Rotational_speedhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/File:Cambio_H.jpghttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Rotational_speedhttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Motor_vehiclehttp://en.wikipedia.org/wiki/Drive_trainhttp://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-2http://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-2http://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-2http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Speedhttp://en.wikipedia.org/wiki/Gear_trainhttp://en.wikipedia.org/wiki/Gearhttp://en.wikipedia.org/wiki/Transmission_(mechanics)#cite_note-1http://en.wikipedia.org/wiki/Machine_(mechanical)


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Single-ratio transmissions also exist, which simply change the speed and torque (and

sometimes direction) of motor output.

In motor vehicles, the transmission will generally be connected to the crankshaft of

the engine. The output of the transmission is transmitted via driveshaft to one or

more differentials, which in turn, drive the wheels. While a differential may also provide gear

reduction, its primary purpose is to permit the wheels at either end of an axle to rotate at

different speeds (essential to avoid wheel slippage on turns) as it changes the direction of

rotation.

Conventional gear/belt transmissions are not the only mechanism for speed/torque

adaptation. Alternative mechanisms include torque converters and power transformation (for

example, diesel-electric transmission and hydraulic drive system). Hybrid configurations also

exist.

EXPLANATION

Early transmissions included the right-angle drives and other gearing

in windmills, horse- powered devices, and steam engines, in support of pumping, milling,

and hoisting.

Most modern gearboxes are used to increase torque while reducing the speed of a

prime mover output shaft (e.g. a motor crankshaft). This means that the output shaft of a

gearbox will rotate at a slower rate than the input shaft, and this reduction in speed will

produce a mechanical advantage, causing an increase in torque. A gearbox can be set up to do

the opposite and provide an increase in shaft speed with a reduction of torque. Some of the

simplest gearboxes merely change the physical direction in which power is transmitted.

Many typical automobile transmissions include the ability to select one of several

different gear ratios. In this case, most of the gear ratios (often simply called "gears") are

used to slow down the output speed of the engine and increase torque. However, the highest

gears may be "overdrive" types that increase the output speed.

http://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Driveshafthttp://en.wikipedia.org/wiki/Differential_(mechanical_device)http://en.wikipedia.org/wiki/Torque_converterhttp://en.wikipedia.org/wiki/Diesel-electric_transmissionhttp://en.wikipedia.org/wiki/Hydraulic_drive_systemhttp://en.wikipedia.org/wiki/Windmillhttp://en.wikipedia.org/wiki/Horsehttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Mill_(grinding)http://en.wikipedia.org/wiki/Hoist_(device)http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Gear_ratiohttp://en.wikipedia.org/wiki/Overdrive_(mechanics)http://en.wikipedia.org/wiki/Overdrive_(mechanics)http://en.wikipedia.org/wiki/Gear_ratiohttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Hoist_(device)http://en.wikipedia.org/wiki/Mill_(grinding)http://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Horsehttp://en.wikipedia.org/wiki/Windmillhttp://en.wikipedia.org/wiki/Hydraulic_drive_systemhttp://en.wikipedia.org/wiki/Diesel-electric_transmissionhttp://en.wikipedia.org/wiki/Torque_converterhttp://en.wikipedia.org/wiki/Differential_(mechanical_device)http://en.wikipedia.org/wiki/Driveshafthttp://en.wikipedia.org/wiki/Crankshaft


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MANUAL TRANSMISSION

A floor-mounted gear lever in a modern passenger car with a manual transmission

A manual transmission, also known as a manual gearbox, stick shift (for vehicles with hand-lever shifters), standard transmission, n-speed manual (n depending on gears) or colloquially

a stick (for hand-shifters), is a type of transmission used in motor vehicle applications. It uses

a driver-operated clutch engaged and disengaged by a foot pedal (automobile) or hand lever

(motorcycle), for regulating torque transfer from the engine to the transmission; and a gear

selector operated by hand (automobile) or by foot (motorcycle).

A conventional, 5 or 6-speed manual transmission is often the standard equipment in a base

model car; other options include automated transmissions such as an automatic

transmission (often a manumatic), a semi-automatic transmission, or a continuously variable

transmission (CVT). The number of gears is often expressed for automatic transmissions as

well (e.g., 3-speed automatic), but without qualifier it usually implies a manual transmission.

OVERVIEW

Manual transmissions often feature a driver-operated clutch and a movable gear stick. Mostautomobile manual transmissions allow the driver to select any forward gear ratio ("gear") at

any time, but some, such as those commonly mounted on motorcycles and some types of

racing cars, only allow the driver to select the next-higher or next-lower gear. This type of

transmission is sometimes called a sequential manual transmission.

The way a manual transmission works is that the flywheel is attached to the engine, the clutch

disk is in between the pressure plate and the flywheel. When running, the clutch disk spins

with the flywheel. As the clutch pedal is depressed, the throw out bearing is pushed in, which

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makes the pressure plate stop applying pressure to the clutch disk. This makes it stop

receiving power from the engine so that the gear can be shifted without damaging the

transmission. When the clutch pedal is released, the clutch disk is allowed to start receiving

power from the engine.

Manual transmissions are characterized by gear ratios that are selectable by locking selected

gear pairs to the output shaft inside the transmission. Conversely, most automatic

transmissions feature epicyclic (planetary) gearing controlled by brake bands and/or clutch

packs to select gear ratio. Automatic transmissions that allow the driver to manually select

the current gear are called Manumatics. A manual-style transmission operated by computer is

often called an automated transmission rather than an automatic.

Contemporary automobile manual transmissions typically use four to six forward gears and

one reverse gear, although automobile manual transmissions have been built with as few as

two and as many as seven gears. Transmissions for heavy trucks and other heavy equipment

usually have at least 8 to 25 gears so the transmission can offer both a wide range of gears

and close gear ratios to keep the engine running in the power band. Operating aforementioned

transmissions often use the same pattern of shifter movement with a single or multiple

switches to engage the next sequence of gear selection. Some manuals are referred to by the

number of forward gears they offer (e.g., 5-speed) as a way of distinguishing between

automatic or other available manual transmissions. Similarly, a 5-speed automatic

transmission is referred to as a "5-speed automatic."

UNSYNCHRONIZED TRANSMISSION(NON-SYNCHRONOUS )

Cherrier two speed gear, circa 1900

The earliest form of a manual transmission is thought to have been invented by Louis-René

Panhard and Émile Levassor in the late 19th century. This type of transmission offered

multiple gear ratios and, in most cases, reverse. The gears were typically engaged by sliding

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them on their shafts (hence the phrase shifting gears), which required careful timing

and throttle manipulation when shifting, so the gears would be spinning at roughly the same

speed when engaged; otherwise, the teeth would refuse to mesh. These transmissions are

called sliding mesh transmissions or sometimes crash boxes, because of the difficulty in

changing gears and the loud grinding sound that often accompanied. Newer manual

transmissions on cars have all gears mesh at all times and are referred to as constant-mesh

transmissions, with "synchro-mesh" being a further refinement of the constant mesh

principle.

In both types, a particular gear combination can only be engaged when the two parts to

engage (either gears or clutches) are at the same speed. To shift to a higher gear, the

transmission is put in neutral and the engine allowed to slow down until the transmission parts for the next gear are at a proper speed to engage. The vehicle also slows while in neutral

and that slows other transmission parts, so the time in neutral depends on the grade, wind,

and other such factors. To shift to a lower gear, the transmission is put in neutral and the

throttle is used to speed up the engine and thus the relevant transmission parts, to match

speeds for engaging the next lower gear. For both upshifts and downshifts, the clutch is

released (engaged) while in neutral. Some drivers use the clutch only for starting from a stop,

and shifts are done without the clutch. Other drivers will depress (disengage) the clutch, shiftto neutral, then engage the clutch momentarily to force transmission parts to match the engine

speed, then depress the clutch again to shift to the next gear, a process called double

clutching. Double clutching is easier to get smooth, as speeds that are close but not quite

matched need to speed up or slow down only transmission parts, whereas with the clutch

engaged to the engine, mismatched speeds are fighting the rotational inertia and power of the

engine.

Even though automobile and light truck transmissions are now almost universally

synchronized, transmissions for heavy trucks and machinery, motorcycles, and for dedicated

racing are usually not. Non-synchronized transmission designs are used for several reasons.

The friction material, such as brass, in synchronizers is more prone to wear and breakage than

gears, which are forged steel, and the simplicity of the mechanism improves reliability and

reduces cost. In addition, the process of shifting a synchromesh transmission is slower than

that of shifting a non-synchromesh transmission. For racing of production-based

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transmissions, sometimes half the teeth on the dog clutches are removed to speed the shifting

process, at the expense of greater wear.

Heavy duty trucks often use unsynchronized transmissions, though military trucks usually

have synchronized transmissions, allowing untrained personnel to operate them in

emergencies. In the United States, traffic safety rules refer to non-synchronous

transmissions in classes of larger commercial motor vehicles. In Europe, heavy duty trucks

use synchronized gearboxes as standard.

Similarly, most modern motorcycles use unsynchronized transmissions: their low gear

inertias and higher strengths mean that forcing the gears to alter speed is not damaging, and

the pedal operated selector on modern motorcycles, with no neutral position between gears

(except, commonly, 1st and 2nd), is not conducive to having the long shift time of a

synchronized gearbox. On bikes with a 1-N-2(-3-4...) transmission, it is necessary either to

stop, slow down, or synchronize gear speeds by blipping the throttle when shifting from 2nd

into 1st.

SYNCHRONIZED TRANSMISSION

Top and side view of a typical manual transmission, in this case a Ford Top loader, used in

cars with external floor shifters.

Most modern manual-transmission vehicles are fitted with a synchronized gear box.

Transmission gears are always in mesh and rotating, but gears on one shaft can freely rotate

or be locked to the shaft. The locking mechanism for a gear consists of a collar (or dog collar)

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on the shaft which is able to slide sideways so that teeth (or dogs) on its inner surface bridge

two circular rings with teeth on their outer circumference: one attached to the gear, one to the

shaft. When the rings are bridged by the collar, that particular gear is rotationally locked to

the shaft and determines the output speed of the transmission. The gearshift lever manipulates

the collars using a set of linkages, so arranged so that one collar may be permitted to lock

only one gear at any one time; when "shifting gears", the locking collar from one gear is

disengaged before that of another is engaged. One collar often serves for two gears; sliding in

one direction selects one transmission speed, in the other direction selects another.

In a synchromesh gearbox, to correctly match the speed of the gear to that of the shaft as the

gear is engaged the collar initially applies a force to a cone-shaped brass clutch attached to

the gear, which brings the speeds to match prior to the collar locking into place. The collar is prevented from bridging the locking rings when the speeds are mismatched by synchro rings

(also called blocker rings or baulk rings, the latter being spelled balk in the U.S.). The

synchro ring rotates slightly due to the frictional torque from the cone clutch. In this position,

the dog clutch is prevented from engaging. The brass clutch ring gradually causes parts to

spin at the same speed. When they do spin the same speed, there is no more torque from the

cone clutch and the dog clutch is allowed to fall into engagement. In a modern gearbox, the

action of all of these components is so smooth and fast it is hardly noticed.

The modern cone system was developed by Porsche and introduced in the 1952 Porsche 356;

cone synchronisers were called Porsche-type for many years after this. In the early 1950s,

only the second-third shift was synchromesh in most cars, requiring only a single synchro and

a simple linkage; drivers' manuals in cars suggested that if the driver needed to shift from

second to first, it was best to come to a complete stop then shift into first and start up again.

With continuing sophistication of mechanical development, fully synchromesh transmissions

with three speeds, then four, and then five, became universal by the 1980s. Many modern

manual transmission cars, especially sports cars, now offer six speeds. The 2012 Porsche 911

offers a seven-speed manual transmission, with the seventh gear intended for cruising- top

speed being attained on sixth.

Reverse gear is usually not synchromesh, as there is only one reverse gear in the normal

automotive transmission and changing gears into reverse while moving is not required - and

often highly undesirable, particularly at high forward speed. Additionally, the usual method

of providing reverse, with an idler gear sliding into place to bridge what would otherwise be

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two mismatched forward gears, is necessarily similar to the operation of a crash box. Among

the cars that have synchromesh in reverse are the 1995-2000 Ford Contour and Mercury

Mystique, '00-'05 Chevrolet Cavalier, Mercedes 190 2.3-16, the V6 equipped Alfa Romeo

GTV/Spider (916),[2] certain Chrysler, Jeep, and GM products which use the New Venture

NV3500 and NV3550 units, the European Ford Sierra and Granada/Scorpio equipped with

the MT75 gearbox, the Volvo 850, and almost all Lamborghinis, Hondas and BMWs.

AUTOMATIC TRANSMISSION

An 8-gear automatic transmission

An automatic transmission (also called automatic gearbox) is a type of motor

vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing

the driver from having to shift gears manually. Like other transmission systems on vehicles, it

allows an internal combustion engine, best suited to run at a relatively high rotational speed,

to provide a range of speed and torque outputs necessary for vehicular travel.

The most popular form found in automobiles is the hydraulic automatic transmission. Similar

but larger devices are also used for heavy-duty commercial and industrial vehicles and

equipment. This system uses a fluid coupling in place of a friction clutch, and accomplishinggear changes by locking and unlocking a system of planetary gears. These systems have a

defined set of gear ranges, often with a parking pawl that locks the output shaft of the

transmission to keep the vehicle from rolling either forward or backward. Some machines

with limited speed ranges or fixed engine speeds, such as some forklifts and lawn mowers,

only use a torque converter to provide a variable gearing of the engine to the wheels.

Besides the traditional automatic transmissions, there are also other types of automated

transmissions, such as a continuously variable transmission (CVT) and semi-automatic

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transmissions, that free the driver from having to shift gears manually, by using the

transmission's computer to change gear, if for example the driver were redlining the engine.

Despite superficial similarity to other transmissions, automatic transmissions differ

significantly in internal operation and driver's feel from semi-automatics and CVTs. In

contrast to conventional automatic transmissions, a CVT uses a belt or other torque

transmission scheme to allow an "infinite" number of gear ratios instead of a fixed number of

gear ratios. A semi-automatic retains a clutch like a manual transmission, but controls the

clutch through electrohydraulic means. The ability to shift gears manually, often via paddle

shifters, can also be found on certain automated transmissions (manumatics such

as Tiptronic), semi-automatics (BMW SMG), and CVTs (such as Lineartronic).

The automatic transmission was invented in 1921 by Alfred Horner Munro of Regina,Saskatchewan, Canada, and patented under Canadian patent CA 235757 in 1923. (Munro

obtained UK patent GB215669 215,669 for his invention in 1924 and US patent 1,613,525 on

4 January 1927). (An earlier patent by Henry R. Hoffman of Chicago was filed on November

12, 1921 and patented on November 27, 1923. The Patent Office then approved two more

Hoffman patents that improved on his device in 1924 and 1925. Hoffman's invention had the

clutch arranged "to selectively engage and drive the differential shaft dependent upon the

speed at which the differential shaft operates."*/


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DESIGN OF PROJECT

The project is done as a table top on the FIAT car’s gear box. The project design

comprises of designing the following parts,

a) Hydraulic circuit

b) Electronic circuit

c) Mechanical components

HYDRAULIC CIRCUIT

Hydraulic motion is selected for gear shifting owing to its large load acceptance and

ease of adaptability in the car. Also the gear shift should be quick. The basic components

design is explained in detail.

SELECTION OF PUMP

Selection of pump is based on following characteristics:

1. Select the actuator that is appropriate based on loads encountered.

2. Determine the flow rate requirements. This involves the calculation of the flow rate

necessary to drive the actuator to move the load through a specified distance within the

given time.

3. Determine the pump speed and select the prime mover. This, together with the flow rate

calculation, determines the pump size

4. Select the pump based on application

5. Select the system pressure. These involves in with the actuator size and magnitude of

the resistive force produced by the external load on the system. Also involved here is

the total amount of power to be delivered by the pump.

6. Select the reservoir and associated plumping, including piping, valving, hydraulic

cylinders, motors and other miscellaneous components.

7. Calculate the overall cost of the system.

8. Consider factors such as noise levels, horse power loss, need for a heat exchanger due

to heat generated, pump wear, scheduled maintenance service to provide a desired life

of the total system.


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HYDRAULIC CIRCUIT DIAGRAM

Hydraulic circuit diagram of the project

1. Reservoir. 7. Cylinder piston assembly

2. Pump. 8. Limit Switch

3. Clutch 9. Gear Box

4. Engine 10. Gear selector rod

5. Inlet Solenoid Valve 11. Spring

6. Outlet Solenoid Valve

9

6

5

7

2 3 4

1

8

10

11


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Reservoir: The hydraulic fluid reservoir holds excess hydraulic fluid to accommodate

volume changes from: cylinder extension and contraction, temperature driven expansion and

contraction, and leaks. The reservoir is also designed to aid in separation of air from the fluid

and also work as a heat accumulator to cover losses in the system when peak power is used.Design engineers are always pressured to reduce the size of hydraulic reservoirs, while

equipment operators always appreciate larger reservoirs. Reservoirs can also help separate

dirt and other particulate from the oil, as the particulate will generally settle to the bottom of

the tank. Some designs include dynamic flow channels on the fluids return path that allow for

a smaller reservoir.

Pump: Hydraulic pumps are used in hydraulic drive systems and can be hydrostatic or

hydrodynamic. A hydraulic pump is a mechanical source of power that converts mechanical

power into hydraulic energy (hydrostatic energy i.e. flow, pressure). It generates flow with

enough power to overcome pressure induced by the load at the pump outlet. When a

hydraulic pump operates, it creates a vacuum at the pump inlet, which forces liquid from the

reservoir into the inlet line to the pump and by mechanical action delivers this liquid to the

pump outlet and forces it into the hydraulic system. Hydrostatic pumps are positive

displacement pumps while hydrodynamic pumps can be fixed displacement pumps, in which

the displacement (flow through the pump per rotation of the pump) cannot be adjusted,

or variable displacement pumps, which have a more complicated construction that allows the

displacement to be adjusted. Although, hydrodynamic pumps are more frequent in day to day

life. Hydrostatics pump which are of various types works on the principle of Pascals law. It

states that the increase in pressure at one point of the enclosed liquid in equilibrium of rest is

transmitted equally to all other points of the liquid, unless the effect of gravity is

neglected.(in case of statics)

Clutch: Clutch is a mechanical device that engages and disengages the power transmission,

especially from driving shaft to driven shaft. Clutches are used whenever the transmission of

power or motion must be controlled either in amount or over time (e.g., electric screwdrivers

limit how much torque is transmitted through use of a clutch; clutches control whether

automobiles transmit engine power to the wheels). In the simplest application, clutches

connect and disconnect two rotating shafts (drive shafts or line shafts). In these devices, one

shaft is typically attached to an engine or other power unit (the driving member) while the

other shaft (the driven member) provides output power for work. While typically the motions

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involved are rotary, linear clutches are also possible. In a torque-controlled drill, for instance,

one shaft is driven by a motor and the other drives a drill chuck. The clutch connects the two

shafts so they may be locked together and spin at the same speed (engaged), locked together

but spinning at different speeds (slipping), or unlocked and spinning at different speeds

(disengaged).

Engine: An engine, or motor, is a machine designed to convert one form

of energy into mechanical energy. Heat engines, includinginternal combustion

engines and external combustion engines (such as steam engines) burn a fuel to create heat,

which then creates a force. Electric motors convert electrical energy

into mechanical motion, pneumatic motors use compressed air and others — such

as clockwork motors in wind-up toys — use elastic energy. In biological systems, molecular

motors, like myosin’s in muscles, use chemical energy to create forces and eventually

motion.

Solenoid Valve: A solenoid valve is an electromechanically operated valve. The valve is

controlled by an electric current through a solenoid: in the case of a two-port valve the flow is

switched on or off; in the case of a three-port valve, the outflow is switched between the two

outlet ports. Multiple solenoid valves can be placed together on a manifold.

Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to

shut off, release, dose, distribute or mix fluids. They are found in many application areas.

Solenoids offer fast and safe switching, high reliability, long service life, good medium

compatibility of the materials used, low control power and compact design.

Besides the plunger-type actuator which is used most frequently, pivoted-armature actuators

and rocker actuators are also used.

Cylinder piston assembly

Cylinder barrel: The main function of cylinder body is to hold cylinder pressure. The

cylinder barrel is mostly made from a seamless tube. The piston reciprocates in the cylinder.

Cylinder base or cap: The main function of the cap is to enclose the pressure chamber at one

end. The cap is connected to the body by means of welding, threading, bolts, or tie rod. Caps

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Webster defines transmission as an assembly of parts including the speed-changing gears and

the propeller shaft by which the power is transmitted from an engine to a live

axle. Often transmission refers simply to the gearbox that uses gears and gear trains to

provide speed and torque conversions from a rotating power source to another device.

Gear selector rod: The gear selector rod connects the gear selector box on the outside of

the motor, with the gear cog selector cruciform inside the motor. This enables the cruciform

to be placed exactly in position within the desired gear cog on the output shaft every time you

change gear and make sure that the power of the motor can be effectively transmitted through

the desired gear, to the output shaft, and finally the rear wheel. Always make sure you order

the gear selector rod specific to your type of engine. Otherwise the gears will not remain

selected and will jump out during use.

Spring: A spring is an elastic object used to store mechanical energy. Springs are usually

made out of spring steel. There are a large number of spring designs; in everyday usage the

term often refers to coil springs. Small springs can be wound from pre-hardened stock, while

larger ones are made from annealed steel and hardened after fabrication. Somenon-ferrous

metals are also used including phosphor bronze and titanium for parts requiring corrosion

resistance and beryllium copper for springs carrying electrical current (because of its lowelectrical resistance). When a coil spring is compressed or stretched slightly from rest,

the force it exerts is approximately proportional to its change in length (this approximation

breaks down for larger deflections).

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ELECTRONIC CIRCUIT

The electronic circuit is used for governing the hydraulic operation. For this purpose

we have used two solenoid valves (inlet and outlet) for each gear to be shifted. The supplyvoltage is from battery which is 12V. there will be six buttons 1, 2, 3, 4, R, N for gear

shifting. Each actuates the gear corresponding when pressed.

The diagram below shows the electronic circuit for various operation of the gear

shifter.

i. Engaging fi rst gear

ii . Maintaining gear positi on

ii i. Releasing gear-neutral positi on

Sole212 V

C

Sole1

12 V

C

Sole1

12 V


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iv. Gear changing

MECHANICAL COMPONENTS

The main mechanical component for the project is the spring. The spring is used to

counter balance the force exerted by the piston. Moreover it is useful in the return motion of

the gear selector rod during gear disengagement. Presence of spring on the gear selector rod

helps in the quick action that is required during the gear shift.

Sole1

12 VC

Sole2


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WORKING PRINCIPLE

1) The main driving force for the gear shifting is by the hydraulic fluid.

2) The gear shifting along with the clutch operation works with the pressing of buttons.

3) On pressing the button corresponding to the gear, three operations take place,

a) Engine rotation

b) Clutch engagement

c) Pump rotation

4) When the car is switched on the engine rotates, on pressing the button clutch engages.

5)

Now electromagnetic clutch engages the pump.

6) Due to the pump rotation the hydraulic fluid is pumped from reservoir to the inlet

solenoid valve.

7) Through this valve the fluid pushes the piston in the cylinder.

8) This motion causes the gear shifter rod to engage the gear which is fitted to the piston.

9)

In order to avoid slippage of gear a limit switch is used to sense the position of selector

rod and cut off the supply.

10) To bring the car to neutral position we press the N button.

11) Now the outlet solenoid valve energizes so the fluid in the cylinder rushes back to the

sump with the aid of spring tension.

12) If the next higher gear has to be selected, the same operation takes place on pressing the

next button.


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ADVANTAGES AND DISADVANTAGES

Merits

A clear alternative for Auto Transmission. This is much cheaper and user friendly withmore features.

Leg room for passengers at front is increased more since the removal of gear rod.

Ease of operation, by the use of feather touch buttons.

A boon for the handicapped, the car can be driven even with only one hand since buttons

are used for changing gears.

No loss in mileage of the car as the load required for gear shift is meagre.

Gear shift is sequential, so no problem of wrong gear selection.

Demerits

Since the project is custom made, it requires a skilled technician to assemble the set

up in the car, considering the space constraints. Moreover the driver should be well

trained in using the system to avoid malfunction.

If there is any misbehavior of a person who is near to the driver, it will create an

automatic change of gear. so it must be considered.


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REFERENCE

1. Robert ball, “Vehicles with Automatic Transmission”

2. Gupta R.B., “Automobile Engineering Drawing”

3. Kirpal Singh., “Automobile Engineering”

4. Anthony Esposito., “Fluid Power with Applications”

5.

Andrew Parr., “Hydraulic and Pneumatic”

power assisted gear shifting

Documents

Transcript of power assisted gear shifting