Vehicle for the verification of truck scales

WOLFHARD GÖGGE and DETLEF SCHEIDT, Verification Authority of Rhineland-Palatinate, Bad Kreuznach, Germany

Rhineland-Palatinate, one of the 16 States of the Federal Republic of Germany (surface area about 20 000 km2 – population four million) has about 1 200 truck scales. This means that a large number of initial verifications and (at 3-yearly intervals) subsequent verifications have to be carried out. According to the corresponding European Union recommendations, the initial verification may be carried out by the manufacturer if a recognized quality management system is used, provided that the process is supervised by the Verification Authority.

Market surveillance, i.e. the question of how the truck scales will metrologically function over a long period of time, is carried out by the Verification Authority. One tool is subsequent verification every third year, using standard weights that have been tested by the Authority. However, the verification of truck scales requires the use of weights with large nominal values (between 100 kg and 1 000 kg) and in order to move such heavy weights, auxiliary equipment has to be installed on the truck.

In principle it is imaginable that platform weighing machines may be tested without weights using hydraulic load installations, though up to now nobody has developed such a system. Nowadays almost all balances are provided with electronic equipment that can be tested relatively easily in the Verification Authority laboratory. However, this cannot substitute a complete check with standard weights at the site of a truck scale. This means that for truck scales to be verified, weights will still have to be transported, moved and loaded on site in the future.

This article concerns a Rhineland-Palatinate Verification Authority vehicle that has been in service for some years (see article in the OIML Bulletin No. 114, March 1989) and which was completely modified about two years ago; meanwhile much experience has been gathered with this new verification vehicle. A normal truck can be used for the construction of a verification vehicle, but with the following special features incorporated:

• Small distance between axles, so that high loads can be moved even onto small weighbridges;

• High-powered engine, so that the vehicle can be driven on public roads without slowing down other traffic (despite its heavy weight);

• Remote-controlled hydraulic crane;

• Supports that can be raised by hydraulic jacks for safe operation of the crane;

• Additional hydraulic supports for lifting up the truck’s front axle, so that the necessary weights can be loaded even on very short weighbridges;

• The ratio of the standard weights compared to the weight of the truck when empty should be about 1:1. In this case the application of the substitution method according to OIML Recommendation R 76 is simple; and

• Removable top cover for easy unloading of the weights. For the verification vehicle in question (Fig. 1) all these aspects have been taken into account and therefore:

Verification vehicle. On the tractor: 25 rolling weights (500 kg each); on the trailer: 15 t block weights, forklift and passenger car

Fig. 1 Verification vehicle. On the tractor: 25 rolling weights (500 kg each);

on the trailer: 15 t block weights, forklift and passenger car

• The distance between axles is 4.55 m. Additional hydraulic supports are mounted behind the front wheels to lift up the front axle (Fig. 2);

Additional hydraulic support for lifting up the front axle
High Denominational Weights

Fig. 2 Additional hydraulic support for lifting up the front axle

• Engine power is 368 kW (500 bhp); and

• Maximum crane load (depending on the working radius) is between 1.6 t and 0.5 t for 3.6 m up to 8 m (Fig. 3)

Unloading two rolling weights using a remote-controlled crane
High Denominational Weights

Fig. 3 Unloading two rolling weights using a remote-controlled crane

Trailer: block weights beneath the passenger car and to the right and left of the forklift, which is standing on the loading area
High Denominational Weights

Fig. 4 Trailer: block weights beneath the passenger car and to the right and left of the forklift, which is standing on the loading area

The crane is operated by remote control, and the truck is equipped with supports which can be hydraulically drawn out when the crane is operating; the handling platform is equipped with an awning.

The loading area of the truck serves for the transport of weights of 12.5 t in the form of 500 kg cylindrical weights. The empty weight of the truck is also 12.5 t, therefore the maximum weight is 25 t.

In order to be able to perform the testing procedure as prescribed, the necessary rolling weights have to be manipulated on the bridge without the use of any mechanical device after they have been unloaded using the crane. However, it transpired that there are not enough auxiliary personnel able to move the heavy weights and that the latter involve a high accident risk when they start rolling unintentionally (in Germany two people were killed by rolling weights).

The former truck scales verification equipment was equipped with rolling weights only. To counter the aforementioned problems, the trailer has been modified to cater for the safe handling of rolling weights. However, the tractor itself is still equipped with rolling weights just in case this facility is required under special circumstances.

The trailer was custom-designed so that it can also be used for the verification of small weighbridges; for this purpose supports are mounted on the trailer directly behind the front axle so that the trailer fits on a weighbridge of 4.10 m in length. The trailer has a total weight of 30 t, of which 15 t are standard block weights of 200 kg, 500 kg and 1 000 kg (Fig. 4). Because of the supports on the tractor and trailer it is possible to verify weighbridges even with very short platforms, i.e. a total load of 55 t (Fig. 5) on a weighbridge of length 8.80 m and a load of 44 t on a weighbridge of length 5 m.

Rear view of the trailer
H D Weights

Fig. 5 Rear view of the trailer

Using block weights reduces the risk of accidents, but on the other hand the disadvantage is that they cannot be moved manually so this is done by a forklift with a loading capacity of 3 t. The forklift is used for loading and unloading the trailer (Fig. 6) as well as for positioning and removing weights on particular spots of the weighbridge according to the verification officer’s instructions (Fig. 7).

Unloading a 1 t block weight
High Denominational Weights

Fig. 6 Unloading a 1 t block weight

The forklift is stored along with the trailer and is operated by the driver of the verification vehicle – therefore external auxiliary personnel for moving the weights are no longer necessary.

Moving standard weights to special spots on the weighbridge
Standard Weights

Fig. 7 Moving standard weights to special spots on the weighbridge

When work with the forklift is finished, it is put back on the trailer using two ramp rails which can be moved up and down hydraulically. Since the forklift cannot mount such a steep ramp by itself, it is pulled up by an electric winch (Fig. 8). The remote control for this winch is operated by the driver of the forklift.

Forklift pulled up by a winch
H D Weights

Fig. 8 Forklift pulled up by a winch

On a rack above the block weights there is also space to store a small car (Fig. 4). This has the advantage that the verification vehicle, which due to its exceptionally high load of 55 t is only allowed to use public roads with special authorization, can directly drive from one operation to the next. For all other trips – for example to a verification office or back home – the driver uses this car. Consequently the verification vehicle itself is only used when absolutely necessary.

Car driving up
H D Weights

Fig. 9 Car driving up

Car in its final position on the trailer (beneath the car, winch for pulling up the forklift
Standard Weights

Fig. 10 Car in its final position on the trailer (beneath the car, winch for pulling up the forklift)

The car has to be small enough to fit on the trailer, and since most of the time it is only used by one person, this does not pose a problem. The car in question is a Fiat Cinquecento with 40 kW (55 bhp) which is able to mount the two ramp rails (Figs. 9 and 10).

If necessary, the driver may spend the night in the driver’s cab, which is quite comfortable. He can be reached at any time using a mobile phone.

The cylindrical and block weights on these vehicles are all standard weights and are tested and adjusted every six months by the Verification Authority. As permissible tolerances, the mpe in accordance with OIML R 47 is applied.

The running costs for the verification vehicle are 1 180 DM per day. If this is considered too high, the weights may be picked up at the Verification Office by the truck scale owner, who must ensure that he is equipped with a forklift, a crane and, of course, a truck to transport the weights. He must also use his own personnel to move and place them, and must later return them to the Verification Office.

The Rhineland-Palatinate Authority verification vehicle is fully booked throughout the year, except when repairs and maintenance work have to be carried out. The percentage of annual utilization is actually greater than 100 % since weighbridges are not only verified on weekdays but also on some weekends (on 23 Saturdays and Sundays in 1998). Weekend operation can be necessary because some companies cannot put their weighing instruments out of operation for a long time for maintenance and verification (on average 1.5 days) during the week. Therefore, they prefer to pay an extra charge for the weekend service.

A verification vehicle costs about 680 000 DM to purchase; annual income is about 290 000 DM less operating costs but including maintenance costs. This means that the vehicle costs are depreciated after approximately 8 years.

The verification vehicle (including the driver) is selffinancing – financial support is only necessary from the government for the initial capital – therefore outright purchasing is highly recommended.

The verification vehicle is also occasionally used for testing truck scales during the 3-year period. This is a chance to study the metrological behavior of road vehicle weighers during this period until the next subsequent verification is due.

Private companies own similar vehicles for testing truck scales and it is up to the owner of the truck scale whether he uses a privately operated vehicle or if he prefers the Verification Office one, but the periodical reverification itself is always carried out by an inspector of the Verification Authority.

For your requirements of High Denominational Standard Weights, you may contact:

Metrication in Weighing & Measuring System in India

WEIGHTS play a vital role in the Society. Normally we use it to judge the cost of products while selling or buying. During the ancient period transactions of commodities were being made either through the “Exchange” or “Barter” system which failed to satisfy the need of a common man of the Society. It laid down the foundation of a system of weighment and measurement. But every social structure/Elaka (region) period gave rise to their own system throughout the whole world which could satisfy their local needs to some extent only but failed to cope up with inter-regional/ inter-state or international trade as the world was coming closer very fastly.

The French Scientists encouraged by the revolution; assigned themselves to the task of evolving a system using nature as model and natural phenomena as guide to discourage the national/regional susceptibilities, if any. The credit goes to Talleyrand, that in 1790, the French Constituent Assembly took the initiative and entrusted the uphill task of establishing a Weighing/Measuring unit/system which may have global acceptance.

After careful examination of various reports submitted by groups of leading scientists of that era, 1/10th million part of a quadrant of the earth’s meridian was adopted as the unit of length “The Metre”. The unit of mass was derived from this unit of length by defining a “Kilogram” as equal to the mass of water at its freezing point having a volume of a decimetre (1/10th of a metre) cube.

Based on the conclusions of aforesaid observations, two physical prototype Standards of Platinum one for ‘Metre’ and other for “Kilogram” were constructed and deposited in the Archives of the French Re public in 1799. Despite the fact that the “Metric System” was the most scientific and its fractions & multiples were based on decimal system, it could not get wide range acceptance by all the advanced countries due to their own socio-political reasons. Many learned scientists of France as well as other European Countries advocated and raised their voice in favour of a uniform measuring system based on “Metric System”, the system remain dormant for several years.

In 1870 the French Government took the initiative and organized a convention in Paris which was attended by 15 countries. In 1872 another convention was held with the participation of delegates from 30 countries, 11 of whom were from American continent. Finally on 20th May 1875 a “Convention du Metre” was signed by 18 countries. The signatory states not only bound themselves with the adoption of Metric system but agreed to form a permanent scientific body at Paris. Thus Bureau International des poidsetmeansures (BIPM) came into existence. So manifest were its advantages that by 1900 as many as 38 countries adopted this system in principle. This figure was doubled in the following fifty years.

Despite having all the positive aspect this “Metric System” could not be conceived and encouraged by the then “British Rulers” of India, rather they encouraged the “Zamindars” the local rulers to develop their own system of weighment and measurement. This was nothing but the famous “Divide & Rule” policy which kept these so called local rulers separate and discourage them coming on a common platform with a common uniform sense of understanding

But this phase could not last long. The interim Govt. adopted a resolution (Resolution No. 0-1-Std (4) 45 dt. 3rd Sept. 1946) which laid the foundation of National Standards Body. The purpose of this body was “to consider and recommend to Govt. of India National Standards for the measurement of length, weight, volume and energy”.

Indian Standard Institute started functioning in June 1947. Dr. Verman, the then Director of the Institute prepared a report in which he advised to adopt the Metric System and its fractions and multiples with Indian nomenclature. Just after independence a sample survey was con ducted which revealed that at least 150 different types of weight system were in use in different parts of the country Strange to note that most of these weights were having the same nomenclature but differ in actual weight markedly For example more than 100 types of “mounds” were in use ranging from 280 “tolas” to 8320 “tolas” a piece in Weight as compared to the standard mound of 3200 tolas. This system was traditional bound and not only exploiting the illiterate people but also encouraging the way to certain known malpractices. For instance, while buying the products from the producers they use the “Seer/mound” of higher weight value where as a lower weight value of Seer/mound were used while delivering these things to the consumers. In both the cases the powerful “Trader body” was benefited. It was felt by our national leaders that unless an uniform scientific system of weighment  & measurement is adopted the interest of the producers as well as consumers cannot be fully protected which was essential for the sound economic growth of the society and the country as a whole.

To implement the uphill task for introducing a systematic and uniform way of weighment and measurement, a Central Metric Committee was constituted under the chairmanship of Union Ministry of Commerce and Industry with several Central Govt. dept., State Govt. Scientists Technocrats, representatives from trade and industry as well as ordinary consumers as its members

After several meetings, marathon discussion and taking several aspects and arguments of different participants in consideration, the “Metric System” came into effect. A resolution was passed by both the houses of Parliament. On 28th December, 1956, it got consent of the President of India with the remarks that “An Uniform System of Weighing & Measuring in metric be introduced throughout all the states and union territories of India”

The Indian Standards Institute was entrusted to prepare the Standards of Weights & Measures & the Indian Weights & Measures Act 1956 was promulgated with the following preamble

i) To use an uniform system of Weights &Measures.

ii) To make greater order and efficiency in economic management like industrial production, trade and even in running a household.

ii) To fully protect the interest of producers and consumers.

iv) To develop trade with other countries of world.

v) To put the country on the map of matriculation in the world.

A sufficient number of enforcing officers were recruited and trained at ILM, as per provisions of the Act for better and uniform implementation of Metric system.

We are Manufacturer- Exporter of Standard Weights, Roller Weights, Cylindrical Weights, Slotted Weights, Test Weights ranging from 1 mg to 1000 kg in all accuracy classes.

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Why Calibration and adjustment are two separate things?

We calibrate a weighing device to understand how it behaves but we adjust the device to change its behavior. So to change the behavior of something firstly, we need to find how it is behaving by calibration and then we can adjust the same. It is important to find the device’s behavior before making any changes to its behavior. Therefore, it is reasonable and common to calibrate a weighing device without adjusting it.

A relationship is developed between a known value (standard) and a measured value by the help of calibration.

 Adjusting a balance means that you are intervening in the weighing system, to make sure that the display is set to show the correct nominal value. And Calibration, on the other hand you are testing whether the display is correct and documenting any deviation.

 For all units of measurement, there are some standards established as the basis for a particular unit.  In the context of weighing devices, standard come in the form of Test Weights. The Test Weight is only classified as checking equipment if it has relevant proof of accuracy.  The Test Weight has a certified value and the weighing device is supposed to indicate a value of Test Weight once it is placed upon the weighing device’s receptor. This is how we understand the behavior of the weighing device by calibration using Test Weight of certified value.

 We find a relationship between the certified value of Test Weight and the value indicated by the weighing device and finally we can also make analysis on the behavioral aspects of the weighing device.

Selection of appropriate Test Weight is very necessary for your balance. A balance can never be more accurate than the Test Weight used to adjust it, it depends on its tolerance. Accuracy of the Test Weight should correspond to the readout of the balance, rather than something better. SWPI’s Cast Iron Test Weights are intended for use in the Verification or Calibration of Weights and for use with weighing instruments of medium accuracy class or ordinary class. They are manufactured from high quality cast iron and are free of cracks and pit. 

The proper selection of an appropriate Test Weights involve knowing their proper permissible error limit, which are already set according to the OIML standards according to their class. Test Weights manufacturing as per OIML Recommendation R-111 is our specialty. Shanker Wire Products Industries (SWPI) manufactures exclusively Test Weights since 1961.

The surface quality of the Test Weights also plays an important role in the calibration of the balance. The bottom surface of Test Weight should be perfectly levelled so that it touches the receptor in its totality. SWPI’s Test Weight are well known for its Test Weight with satisfactory surface quality which ensures the accurate calibration of the weighing device.

Adjustment is not calibration. You can calibrate a measurement device without adjusting it. Calibration is developing an understanding of a measurement device. Calibration should include the determination of the measurement uncertainty to enhance the understanding of the measuring device.

To enquire about our Calibrated Test Weights follow the link: https://www.weights-swpi.com/contact/

OIML Systems

Basic and MAA Certificates registered

2015.12–2016.02

Information: www.oiml.org section “OIML Systems”

The OIML Basic Certificate System The OIML Basic Certificate System for Measuring Instruments was introduced in 1991 to facilitate administrative procedures and lower the costs associated with the international trade of measuring instruments subject to legal requirements. The System, which was initially called the “OIML Certificate System”, is now called the “OIML Basic Certificate System”. The aim is for “OIML Basic Certificates of Conformity” to be clearly distinguished from “OIML MAA Certificates”. The System provides the possibility for manufacturers to obtain an OIML Basic Certificate and an OIML Basic Evaluation Report (called “Test Report” in the appropriate OIML Recommendations) indicating that a given instrument type complies with the requirements of the relevant OIML International Recommendation. An OIML Recommendation can automatically be included within the System as soon as all the parts – including the Evaluation Report Format – have been published. Consequently, OIML Issuing Authorities may issue OIML Certificates for the relevant category from the date on which the Evaluation Report Format was published; this date is now given in the column entitled “Uploaded” on the Publications Page. Other information on the System, particularly concerning the rules and conditions for the application, issue, and use of OIML Certificates, may be found in OIML Publication B 3 OIML Basic Certificate System for OIML Type Evaluation of Measuring Instruments (Edition 2011) which may be downloaded from the Publications page of the OIML web site.
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Magazine: “Weights & The Society” Volume: 06 & Issue No.: 1

Logo of SWPI    Magazine: Weights & The Society (Volume: 06  & Issue No.: 1)High Denominational Weights

           Published by Shanker Wire Products Industries

 

                                             

                                     GOLDEN JUBILEE CELEBRATIONS OF METRIC SYSTEM IN INDIA

“Legal Metrology – Achievements of India and what it can offer to others.”

Article by:

Sri P.A Krishnamurthy,

Former Director, Legal Metrology, Government of India.      

INTRODUCTION:

The field of ‘Legal Metrology’ or Weights and Measures’ as is known in the common parlance, is the field where measurements are regulated by Government laws for the benefit of all stakeholders. The main object of such regulation is to ensure standardized procedures for calibration acceptable to all stakeholders, transparency in the whole procedure, and accountability of the measurement results. Continue reading “Magazine: “Weights & The Society” Volume: 06 & Issue No.: 1″

How often do I have to calibrate my balance, and what are the risks of not calibrating?

A calibration certificate reports results at the time the calibration was performed. In many cases, the responsible person assumes that the calibration is valid for a year. This leads to the wrong conclusion that a calibration interval of one year is sufficient.

Ideally, calibration intervals are defined following a risk-based methodology, for example, what is the probability of something going wrong and how high is the impact? A high impact and high probability correspond to a high risk, which requires a shorter calibration interval. Otherwise, a low impact and a low probability result in a low risk, allowing intervals to be extended.

High Denominational Weights

To forgo calibration is a high-risk strategy. Hidden costs and risks associated with the un-calibrated balance or scale could be much higher than the cost of calibration itself. Using non-calibrated equipment can lead to production problems such as:

  • Unscheduled downtime
  • Inferior product quality
  • Process and audit issues
  • Product rework and recalls
 

Environmental changes can also lead to undetected drift or increasing random errors that degrade performance. Periodically scheduled calibration along with routine testing (see below) is the best way to reduce calibration-related risk.

To know more you can contact us: https://www.weights-swpi.com/contact/    

Why we need calibration of balance ?

Why would you want to weigh at all if your balance is not calibrated?

Balance or scale calibration is essential to achieve accurate weighing results. Ignoring this important service activity turns to measure into guesswork. In other words, it is negligent to weigh with a non-calibrated balance or scale.

Continue reading “Why we need calibration of balance ?”