1 TABLE OF CONTENTS Acknowledgements ……………………………………………………………………………….. 02Introduction…………………………………………………………………………………………… 03The Automobile Differential………………………………………………………………….. 04-08Introduction …………………………………………………………………………………………………… 04 Inputs and Outputs, paths of power transmission and possible power losses in a differential …………………………………………………….. 05 -06 Reasons for using the specific machine elements ……………………………………………07 Drawbacks and Improvements for a differential ……………………………………………. . 08 Washing Machine ………………………………………………………………………..…….…… 09-15 Introduction ……………………………………………………………………………………… ..……………09 Inputs and Outputs, paths of power transmission and possible power losses in a washing machine……………………….……..…..……….. 10-13 Reasons for using the specific machine elements …………………………...………………13-14 Drawbacks and Improvements for a washing machine ………………….……………….. 15 Lockstitch Machine ……………………………………………………………………..…….…… 16-22 Introduction ……………………………………………………………………………………… ..…….……16-17 Inputs and Outputs, paths of power transmission and possible power losses in a lockstitch machine……………….…….……..…..……….. 18-19 Reasons for using the specific machine elements …………………………...………………20 Drawbacks and Improvements for a lockstitch machine ……………….…….……………21-22
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In automobiles and other wheeled vehicles, a differential couples the drive shaft to half-shafts
that connect to the rear driving wheels. The differential gearing allows the outer drive wheel to
rotate faster than the inner drive wheel during a turn. This is necessary when the vehicle turns,
making the wheel that is travelling around the outside of the turning curve roll farther and fasterthan the other. Average of the rotational speed of the two driving wheel equals the input
rotational speed of the drive shaft. An increase in the speed of one wheel is balanced by a
decrease in the speed of the other. A differential consists of one input, the drive shaft, and two
outputs which are the two drive wheels, however the rotation of the drive wheels are coupled
by their connection to the roadway. Under normal conditions, with small tire slip, the ratio of the
speeds of the two driving wheels is defined by the ratio of the radii of the paths around which
the two wheels are rolling, which in turn is determined by the track-width of the vehicle (the
distance between the driving wheels) and the radius of the turn.
A washing machine (laundry machine, clothes washer, or washer) is a machine to wash laundry,
such as clothing and sheets. The term is mostly applied only to machines that use water as
opposed to dry cleaning (which uses alternative cleaning fluids, and is performed by specialist
businesses) or ultrasonic cleaners. Washing entails immersing, dipping, rubbing, or scrubbing in
water usually accompanied by detergent, or bleach. The simplest machines may simply agitate
clothes in water; automatic machines may fill, empty, wash, spin, and heat in a cycle. Most
washing machines remove substantial amounts of water from the laundry at the end of a wash
cycle, but do not completely dry it.
Sewing machines are something like cars: There are hundreds of models on the market, and
they vary considerably in price and performance. At the low-end of the scale, there are
conventional no-frills electric designs, ideal for occasional home use; at the high-end, there aresophisticated electronic machines that hook up to a computer. Textile companies have many
machines to choose from, including streamlined models specifically designed to sew one
particular product. But just like cars, most sewing machines are built around one basic idea.
Where the heart of a car is the internal, the heart of a sewing machine is the loop stitching
The differential is simply a device that splits the engine torque two ways, allowing each output
to spin at a different speed. The differential is found on all modern cars and trucks, and also in
many all-wheel-drive vehicles. Automobile differentials serve three main purposes, namely;
Aiming the engine power at the wheels Acting as the final gear reduction in the vehicle, slowing the rotational speed of the
transmission one final time before it hits the wheels Transmitting the power to the wheels while allowing them to rotate at different speeds
There are a number of automobile differentials according to the mechanism used. The most
common are;
Open Differentials
Locking Differentials
Limited Slip Differentials(LSD)
Where the open differential always balances the torque between the 2 wheels whereas, locking
differentials adapt to resistance and the LSD (Limited Slip Differential) is a compromise of the 2.
Each have their own advantages and disadvantages.
The third purpose mentioned above is what has earned the differential its name. Since it allows
2 wheels connected to it to be rotated at 2 different speeds. In this section of the report, the
following points shall be taken into account;
Inputs and outputs of a differential
Paths of power transmissions and possible power losses
Reasons for using those machine elements
Drawbacks of a differentials
Improvements to a differential
Furthermore, this differential principle can be applied to front-wheel-drive vehicles, rear-wheel-
drive vehicles and also for all-wheel-drive vehicles. For front wheel and rear wheel drives there
shall be only two side axles connecting to wheels whereas in all-wheel-drive vehicles 4 side axles
need to be connected. These all-wheel-drive vehicles need a differential between each set of
drive wheels, and they need one between the front and the back wheels as well, because thefront wheels travel a different distance through a turn than the rear wheels.
INPUTS AND OUTPUTS, PATHS OF POWER TRANSMISSION AND POSSIBLE POWER
LOSSES IN AN AUTOMOBILE DIFFERENTIAL
In order to completely describe the mechanism of an automobile differential or to put it more
simply, a differential, the following diagram including the basic machine elements shall be used.
Note that this is just a rough sketch and teeth in gearing are usually not parallel teeth.
Car wheels spin at different speeds, especially when turning. Each wheel travels a different
distance through the turn, and that the inside wheels travel a shorter distance than the outsidewheels. Since speed is equal to the distance traveled divided by the time it takes to go that
distance, the wheels that travel a shorter distance travel at a lower speed. Also note that the
front wheels travel a different distance than the rear wheels.
The power generated in the engine is first transmitted to the gear box, and then to the main axle.
Just before the high rotating speeds of the axle hit the epicyclic gear train in the differential, this
provides the final gear reduction, slowing the rotational speed of the transmission one final time.
As shown in the figure above the teeth ratio Pinion gear: Ring gear is rather a small value, thus
resulting in a reduction of high rotational speeds. This also splits the amount of torque
transmitted to each wheel. Hence the input is the pinion gear connected to the main axle and
the output is the rotation of wheels, sometimes in different speeds.
The path of power thus is
The advantage of Epicyclic gear systems, the ability to produce two different output speeds using
a single input speed, has been used here. That is, the Epicyclic gearing produces 2 different output
speeds for the wheels, which is the purpose intended of the differential system. Transmission ofpower inside the Epicyclic gear train is as follows.
POSSIBLE POWER LOSSES
In a system which is not ideal, as a practical automobile differential, power is always lost, mainly
in the form of heat. When a machine is running there are various frictional forces to be overcome,
each of which requires a continuous expenditure of energy, resulting in heating the rubbedelements. These kinds of losses are known as mechanical losses and in systems like this, power
is lost mainly in the form of mechanical losses. There is mechanical/frictional loss in machine
bearings connecting the main axle and the pinion gear and at the surfaces of contact in gears
(pitch points). These losses can depend on the load driven and also the speeds of rotation. Power
could also be loss due to deformations in mechanical elements.
Engine Gear Box Main Axle Pinion Gear
Ring Gear Epicyclic Gear Train Side Axles Wheels
Driver shafts spins the pinion gear
Pinion gear turns the larger ring gear to produce gear reduction
Ring gear attached to the differential case and hence rotates along
with the ring gear
Differential case spins the sun gears which are attached to the axles
Whining or howling noise that changes when going from acceleration to deceleration. Lack ofservice and low fluids can cause this problem.
If backlash (clearance) between the ring gear and the pinion gear is too great, a clunking sound
can be produced, especially when an automatic transmission is shifted into gear.
II. Bearings
Humming sounds get louder with speeds.
III. Mechanism
The torque transmitted to the two wheels with the open differential is the same. Consequently,if one wheel slips, as in ice or mud, the torque to the other wheel is reduced. The slipping wheel
receives all the torque.
IMPROVEMENTS
I. System should be properly lubricated and maintained in order to minimize ring and pinion
problems. I.e. fluid levels should be maintained at optimum levels. Vehicle should be subjected
to service in a timely manner.
II. Backlash should be adjusted to an optimum level. It is needed to allow for the heat expansion
and lubrication. Too little backlash will cause the gears to jam and too much backlash will causegear noise (whirring, roaring and clunking).
III. Normal/Open differentials have a disadvantage in the mechanism as explained above in the
previous section. Engineers have improved this technology to build locking differentials where
the side axle system is locked together and both of the wheels are forced to rotate at the same
speed without giving all the torque to the slipping wheel. Engineers have further improved these
technologies and have now come up with LSDs or Limited Slip Differentials, which is a
compromise of the two, since both the systems have desirable properties.
INPUTS AND OUTPUTS, PATHS OF POWER TRANSMISSION AND POSSIBLE POWER
LOSSES IN A WASHING MACHINE
GEAR BOX
When the washer goes into spin cycle, the whole mechanism locks up, causing everything to spinat the same speed as the input, which is hooked up to the motor. The interesting thing here is
that when the motor spins the gearbox in one direction, the agitator runs, and when it spins it
the other way, the whole machine locks up.
In the figure below there is a gear with angled teeth. There is also a smaller gear with angled
teeth behind the big one in the foreground. These are the only two gears with angled teeth.
Depending on which way the gears are spinning, the angle on the teeth will tend to force the
inner gear to slide either to the left or to the right inside the gearbox.
If it slides to the left, it engages a mechanism that locks up the gearbox.
We can see a small notch in the outer shaft. This notch is hollow, and is attached to the shaft
with the small helical gear. When the small gear moves, it moves this outer shaft with it, and the
small notch engages the single tooth that is fixed to the lockup mechanism. When the gearbox is
locked up, both the inner shaft, which drives the agitator, and the outer shaft, which drives the
tub, spin at the same speed as the input pulley. Also gear box is working under the direct drive
mechanism. It is one that takes the power coming from a motor without any reductions.
Mainly power is losses as the heat in washing machine as in any common mechanical system. But
it is working under direct drive mechanism. So power is less wasted in friction. It is an advantage.
Because of this mechanism it wants precise control. But in a system which is not ideal there is a
considerable power loss due to the friction in belt drives and pulleys also friction in gear drives.Also power is losses as the heat when gear box is being run. In washing machines, unlike in many
common systems, power is also lost as unnecessary vibrations. Although dampers as explained
above have been used in washing machines, washing machines in general, still create a
considerable amount of mechanical vibrations.
REASONS FOR USING THE SPECIFIC MACHINE ELEMENTS
1. Pulleys & Belt drives
Low maintenance since washing machines are not regularly serviced.
They are very simple and economical.
Noise & Vibration are damped out since a considerable noise can be generated in the
FIGURE 1.0 - The conventional single needle lockstitch machine
A lockstitch sewing machine binds cloth together with two spools of thread and a needle with
the eye at its base. Distinct from a chain stitch machine, a lockstitch sewing machine makes
strong, straight seams. It was the first kind of commercial sewing machine to secure a patent,
enter manufacturing, and place automatic sewing in the hands of millions of households. Most
homes have a lockstitch sewing machine because their basic stitch can be used for a wide variety
of applications. The machine works by interlocking two threads from two bobbins that cannot
unravel easily, unlike a chain stitch. The length of the stitch, as well as tautness, can be controlled
by dial.
The first spool sits on top of the machine. Its thread runs through a tension arm to feed itsmoothly. Then it threads into a needle's eye, located at its base. The needle attaches to a foot
that can press the fabric against a feed. The second thread, on another bobbin, is hidden in a
compartment beneath the foot. This thread gets pulled on a shuttle to loop around the thread
from above. The needle stitches up and down either by a manual foot treadle or a motor
INPUTS AND OUTPUTS, PATHS OF POWER TRANSMISSION AND POSSIBLE POWER
LOSSES IN A LOCKSTITCH MACHINE
INPUTS AND OUTPUTS
The main input of the machine, is an electrical motor which then transmits power and drivingforce to the system and the final output is the reciprocatory vertical movement of the needle and
the rotational motion of the bobbin.
PATHS OF POWER TRANSMISSION
The electric motor is connected to a drive wheel via a drive belt. The drive wheel rotates the
length of the top drive which is connected to several different machine elements shaft. The end
of a crank shaft rotates, it drives the needle bar up and down. The thread tensioner arm crank
also moves. Move in synchronization with the needle bar clamp arm reduced to create enough
slack to form a loop in the fabric, and then stops to tighten the loop after it is released from the
shuttle hook.
The wire extends from a reel on the top of the machine, through the clamping arm and via a
tension disc assembly. By rotating the entire disk, the drain can tighten the yarn feed to the
needle. The voltage should be stricter when the thinner and more flexible fabric sewn heavier
fabric while sewing.
The first element along the stem is a single belt which rotates a lower drive shaft. The lower end
of the drive shaft is connected to a bevel gear set which rotates the shuttle assembly. Since the
two are connected to the same shaft, the shuttle assembly and the needle assembly is always
move in unison.
Ties of lower driving operating the feed mechanism shaft is moved. A drop feed slide forward link
and backward at every cycle. Simultaneously, the other link conveyor moves up and down. The
two rods are synchronized such that the drive pressed against the fabric, which moves forward
claw, and then moves downwardly to release the tissue. The conveyor moves rearwardly before
pressing the fabric to repeat the cycle.
The motor is controlled by a pedal, which allows for easily varying the speed of drains. The good
thing about this design is that everything is connected, so that when the pedal is depressed, the
motor accelerates all processes at the same pace. The process is always perfectly synchronized,
increased accuracy of the stop position and stronger material penetrating force of the needle.
The new model control box, which energy-saving mode is provided.
The new models of lockstitch machines which consist of an energy-saving mode, has beendeveloped. This control box is the first one which provides an energy-saving mode for the sewing
machine. The power consumption during standby, when the motor is at rest, is reduced by
approximately 20%. In addition, abundantly incorporated state-of-the-art energy-saving features
such as a compact-in-size solenoid for the auto-lifter allow the machines to reduce power
consumption, to increase productivity and to be friendly to the environment.
Dry technology – Oil stains on the material being sewn are reduced, thereby improving
product quality
The advanced dry technology helps prevent oil stains on the material being sewn. The mainsource of oil stains is the frame. The semi-dry head type sewing machine comes with a frame
which does not need lubrication. The fully-dry head type sewing machine is an even further
evolved dry-head type which comes with a frame and a hook section which do not need
Design for achieving silent operation – The operating noise by the machine is reduced,
helping reduce operator fatigue
One of the eternal challenges of a sewing plant is the improvement of the work environment.
One of the factors to be improved is noise within the plant. The DDL-9000B 1-needle lockstitch
machine is the sewing machine which is used most frequently in the sewing plant. For this reason,the noise generating mechanisms have been attuned to eliminate any harsh noise.
Production support functions – An operation panel is provided with a production
support function
The production support function actually consists of three different functions (six different
modes), which are the output control function, operation measuring function and bobbin counter
function. Each with its own production support effect. An appropriate function (mode) can be
selected as required. The parameter setting can be done on the panel located on the top of the
sewing machine, thereby helping reduce operator fatigue during setup changing.