In 2023, Shenzhen's first large-scale professional exhibition with global influence-Shanghai International Auto Parts, Maintenance, Testing and Diagnosis Equipment and Service Supplies Exhibition will be held at Shenzhen International Convention and Exhibition Center (Bao'an) from February 15th to 18th. This is the first time that the exhibition is held in Shenzhen, covering an area of 210,000 square meters, and it is also one of the largest exhibition projects in South China in February.
It is understood that the exhibition is jointly sponsored by Frankfurt (Shanghai) Co., Ltd. and China National Machinery International Cooperation Co., Ltd. It is not only an industry exhibition with global influence, but also an automobile exhibition integrating information exchange, marketing promotion, business services and industrial education. The whole industry chain service platform.

2023.2.15 The 17th Shanghai Frankfurt Auto Parts Exhibition opens in Shenzhen!

A speedometer or a speed meter is a gauge that measures and displays the instantaneous speed of a vehicle. Now universally fitted to motor vehicles, they started to be available as options in the 1900s, and as standard equipment from about 1910 onwards. Speedometers for other vehicles have specific names and use other means of sensing speed. For a boat, this is a pit log. For an aircraft, this is an airspeed indicator.
Charles Babbage is credited with creating an early type of speedometer, which was usually fitted to locomotives.
The electric speedometer was invented by the Croatian Josip Belu&scaron;ić in 1888 and was originally called a velocimeter.
<h4>Speedometer Operation</h4>
Originally patented by Otto Schultze on 7 October 1902, it uses a rotating flexible cable usually driven by gearing linked to the output of the vehicle's transmission. The early Volkswagen Beetle and many motorcycles, however, use a cable driven from a front wheel.
When the vehicle is in motion, a speedometer gear assembly turns a speedometer cable, which then turns the speedometer mechanism itself. A small permanent magnet affixed to the speedometer cable interacts with a small aluminum cup (called a speedup) attached to the shaft of the pointer on the analog speedometer instrument. As the magnet rotates near the cup, the changing magnetic field produces eddy currents in the cup, which themselves produce another magnetic field. The effect is that the magnet exerts a torque on the cup, "dragging" it, and thus the speedometer pointer, in the direction of its rotation with no mechanical connection between them.
The pointer shaft is held toward zero by a fine torsion spring. The torque on the cup increases with the speed of rotation of the magnet. Thus an increase in the speed of the car will twist the cup and speedometer pointer against the spring. The cup and pointer will turn until the torque of the eddy currents on the cup is balanced by the opposing torque of the spring, and then stop. Given the torque on the cup is proportional to the car's speed, and the spring's deflection is proportional to the torque, the angle of the pointer is also proportional to the speed, so that equally spaced markers on the dial can be used for gaps in speed. At a given speed, the pointer will remain motionless and point to the appropriate number on the speedometer's dial.
The return spring is calibrated such that a given revolution speed of the cable corresponds to a specific speed indication on the speedometer. This calibration must take into account several factors, including the ratios of the tail shaft gears that drive the flexible cable, the final drive ratio in the differential, and the diameter of the driven tires.
One of the key disadvantages of the eddy current speedometer is that it cannot show the vehicle speed when running in reverse gear since the cup would turn in the opposite direction - in this scenario the needle would be driven against its mechanical stop pin on the zero position.
<h4>Electronic Speedometer</h4>
Many modern speedometers are electronic. In designs derived from earlier eddy-current models, a rotation sensor mounted in the transmission delivers a series of electronic pulses whose frequency corresponds to the (average) rotational speed of the driveshaft, and therefore the vehicle's speed, assuming the wheels have full traction. The sensor is typically a set of one or more magnets mounted on the output shaft or (in transaxles) differential crown wheel, or a toothed metal disk positioned between a magnet and a magnetic field sensor. As the part in question turns, the magnets or teeth pass beneath the sensor, each time producing a pulse in the sensor as they affect the strength of the magnetic field it is measuring.[1] Alternatively, particularly in vehicles with multiplex wiring, some manufacturers use the pulses coming from the ABS wheel sensors which communicate to the instrument panel via the CAN Bus. Most modern electronic speedometers have the additional ability over the eddy current type to show the vehicle speed when moving in reverse gear.
A computer converts the pulses to a speed and displays this speed on an electronically controlled, analog-style needle or a digital display. Pulse information is also used for a variety of other purposes by the ECUor full-vehicle control system, e.g. triggering ABS or traction control, calculating average trip speed, or incrementing the odometer in place of it being turned directly by the speedometer cable.
Another early form of electronic speedometer relies upon the interaction between a precision watch mechanism and a mechanical pulsator driven by the car's wheel or transmission. The watch mechanism endeavors to push the speedometer pointer toward zero, while the vehicle-driven pulsator tries to push it toward infinity. The position of the speedometer pointer reflects the relative magnitudes of the outputs of the two mechanisms.
<h4>GPS Speedometer</h4>
GPS devices are positional speedometers, based on how far the receiver has moved since the last measurement. Its speed calculations are not subject to the same sources of error as the vehicle's speedometer (wheel size, transmission/drive ratios). Instead, the GPS's positional accuracy, and therefore the accuracy of its calculated speed, is dependent on the satellite signal quality at the time. Speed calculations will be more accurate at higher speeds when the ratio of positional error to positional change is lower. The GPS software may also use a moving average calculation to reduce error.&nbsp;Some GPS devices do not take into account the vertical position of the car so will underreport the speed by the road's gradient.
As mentioned in the satnav article, GPS data has been used to overturn a speeding ticket; the GPS logs showed the defendant traveling below the speed limit when they were ticketed. That the data came from a GPS device was likely less important than the fact that it was logged; logs from the vehicle's speedometer could likely have been used instead, had they existed.

What is Speedometer?

A tachometer (revolution counter, tach, rev counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated analog dial, but digital displays are increasingly common.
The word comes from Greek &tau;ά&chi;&omicron;&sigmaf; (t&aacute;chos "speed") and &mu;έ&tau;&rho;&omicron;&nu; (m&eacute;tron "measure"). Essentially the words tachometer and speedometer have identical meanings: a device that measures speed. It is by arbitrary convention that in the automotive world one is used for engine revolutions and the other for vehicle speed. In formal engineering nomenclature, more precise terms are used to distinguish the two.
 History
 The first tachometer was described by a Donkin in a paper to the Royal Society of Arts in 1810 for which he was awarded the Gold medal of the society. This consisted of a bowl of mercury constructed in such a way that centrifugal force caused the level in a central tube to fall when it rotated and brought down the level in a narrower tube above filled with colored spirit. The bowl was connected to the machinery to be measured by pulleys.
The first mechanical tachometers were based on measuring the centrifugal force, similar to the operation of a centrifugal governor. The inventor is assumed to be the German engineer Dietrich Uhlhorn; he used it for measuring the speed of machines in 1817.[citation needed] Since 1840, it has been used to measure the speed of locomotives.
<h4> In automobiles, trucks, tractors, and aircraft</h4>
Tachometers or revolution counters on cars, aircraft, and other vehicles show the rate of rotation of the engine's crankshaft, and typically have markings indicating a safe range of rotation speeds. This can assist the driver in selecting appropriate throttle and gear settings for the driving conditions. Prolonged use at high speeds may cause inadequate lubrication, overheating (exceeding capability of the cooling system), and exceeding speed capability of sub-parts of the engine (for example spring retracted valves) thus causing excessive wear or permanent damage or failure of engines. On analog tachometers, speeds above the maximum safe operating speed are typically indicated by an area of the gauge marked in red, giving rise to the expression of "redlining" an engine &mdash; revving the engine up to the maximum safe limit. Most modern cars typically have a revolution limiter which electronically limits engine speed to prevent damage. Diesel engines with traditional mechanical injector systems have an integral governor which prevents over-speeding the engine, so the tachometers in vehicles and machinery fitted with such engines sometimes lack a redline. In vehicles such as tractors and trucks, the tachometer often has other markings, usually, a green arc showing the speed range in which the engine produces maximum torque, which is of prime interest to operators of such vehicles. Tractors fitted with a power take-off (PTO) system have tachometers showing the engine speed needed to rotate the PTO at the standardized speed required by most PTO-driven implements. In many countries, tractors are required to have a speedometer for use on a road. To save fitting a second dial, the vehicle's tachometer is often marked with a second scale in units of speed. This scale is only accurate in a certain gear, but since many tractors only have one gear that is practical for use on-road, this is sufficient. Tractors with multiple 'road gears' often have tachometers with more than one-speed scale. Aircraft tachometers have a green arc showing the engine's designed cruising speed range. In older vehicles, the tachometer is driven by the RMS voltage waves from the low tension (LT contact breaker) side of the ignition coil,[3] while on others (and nearly all diesel engines, which have no ignition system) engine speed is determined by the frequency from the alternator tachometer output. This is from a special connection called an "AC tap" which is a connection to one of the stator's coil outputs, before the rectifier. Tachometers driven by a rotating cable from a drive unit fitted to the engine (usually on the camshaft) exist - usually on simple diesel-engined machinery with basic or no electrical systems. In recent EMS found on modern vehicles, the signal for the tachometer is usually generated from an ECU which derives the information from either the crankshaft or camshaft speed sensor.
<h4> Traffic engineering</h4>
Tachometers are used to estimate traffic speed and volume (flow). A vehicle is equipped with a sensor and conducts "tach runs" which record the traffic data. These data are a substitute or complement to loop detector data. To get statistically significant results requires a high number of runs, and bias is introduced by the time of day, day of the week, and season. However, because of the expense, spacing (a lower density of loop detectors diminishes data accuracy), and relatively low reliability of loop detectors (often 30% or more are out of service at any given time), tach runs remain a common practice

The origin and application of Tachometer

A qualified engine dashboard will tell you the exact engine-related information and the slightest difference will affect the safety of the entire driving, so careless.
How can you tell if an engine dashboard is qualified? Here we share some information about how to select an engine dashboard.
There are various sizes and types of marine instruments on the market, and the general criteria for judging their performance can be seen from these aspects:
High accuracy, especially some unique suspension structures, and removable pointers, enables each instrument to be tested and calibrated independently. It has reliable performance and long service life, and its zero maintenance should be considered in terms of brand and quality.
Intelligent lighting, no solid-state dial lighting is at the top edge, but from the bottom of the translucent dial lighting, so as to achieve the best reading effect.
Waterproof, preferably double-glazed dashboard surface with good waterproof function.
Two circular frames. All instruments have two circular frames. One is made of black plastic and the other is made of chrome-plated plastic. Dimensions can be selected according to preference and hull trim.
In addition to the accurate engine table, the components that make up the engine dashboard need to be equipped with other dashboards to form a complete dashboard. These dials include a tachometer (with timer), hour meter, voltmeter, water temperature gauge, exhaust temperature alarm, ammeter, oil pressure gauge, rudder display, water level indicator, oil level gauges, and wastewater tank meter.
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<h3>Standards to be considered for accessories (examples)</h3>
Tachometer (with timer)
For example, 12/24 V DC is suitable for generators with W joints. It is suitable for diesel engines with a scale of 0-4000r.p.m.
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Hourmeter
Engine hour meter, connected with the ignition switch.
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Voltmeter
For example, it is suitable for 12 or 24 volts of direct current with scales of 10-16 volts and 20-32 volts, respectively.
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Water temp gauge
Generally, it can be applied to 12 or 24 volts DC current with a scale of 40-120 and 105-250. Temperature sensors can also be selected as an option.
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Drainage temperature alarm
It is specially designed for wet exhaust systems. When the temperature of the exhaust hose or muffler exceeds the allowable value, there will be light alarm and sound alarm signals. When two engines are equipped with two sensors, the sensor can be connected with two alarms if necessary, such as when there are two cabs.
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Amperometer
For example scale: +/-60A, 12 or 24 V DC, with the shunt. An ammeter calibrated +/-100A with a separate shunt can also be selected.
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Oil pressure gauge
12 or 24 V DC is optional. Calibration: 0-8kg/c_and 0-110psi. oil pressure sensor can also be used as an option.
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Wastewater tank level gauge
The interface of the wastewater tank can be equipped with warning lights, so that when the water tank is full or not in use,&nbsp; &nbsp;the warning lights will be lit.

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2023.2.15 The 17th Shanghai Frankfurt Auto Parts Exhibition opens in Shenzhen!

What is Speedometer?

The origin and application of Tachometer

How to choose the right engine dashboard?

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