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WHAT IS RIMS PCD, OFFSET & CENTERBORE? DEFINITION & GUIDE TO CHOOSE SPORT RIMS

by kdi · May 20, 2009

Many people are confused with those definition. PCD, OFFSET and CENTERBORE is totally important thing or definition when you are going to buy a new sport rims. Here is some explanation about it and some guide to choose a sport rims that suitable for your car.

WHAT IS RIM PCD, OFFSET & CENTERBORE? DEFINITION & GUIDE TO CHOOSE SPORT RIMS

WHAT IS PCD?

The meaning of PCD? PCD stands for pitch circle diameter and is the diameter of a circle drawn through the centre of your wheel’s bolt holes. ]
P.C.D. is measured in millimeters and also indicate the number of studs or bolts the wheel will have. Proton Alloy Wheels are usually either 4×100: i.e. 4 bolt holes drilled through the centre of an imaginary 100mm circle.
About the holes & bolts attached, most Proton & Perodua Cars have 4 bolts, most U.S. passenger cars have 5 bolts while compact models sometimes have only 4 and pick-up trucks can have as many as 6 or 8. In contrast, some smaller French cars, including the Citroën 2CV, Renault 4 and some Peugeot 106′s and Citroen Saxos only have three which is same with Proton Tiara.

RIM PCD OFFSET AND CENTERBORE OF MAZDA, NISSAN & TOYOTA (picture above)
If you can see the schedule above shows some PCD of cars. The vehicle with more holes like Land Cruiser is because of the SUV needs more strength to hold the rims.
Some aftermarket rim manufacturers do provide universal-fit rims which have elongated lug holes (or 8-10 holes which cover multiple bolt patterns) which will fit a wider-range of vehicles.
The most common PCD values are 100 mm and 114.3 mm. This difference arises from the manufacturers’ measurement convention – whether they are designing around metric values (100 mm) or imperial values (4.5 inches, i.e. 114.3 mm).

RIM PCD OFFSET AND CENTERBORE OF BMW, HONDA, HYUNDAI, KIA(picture above)

WHAT IS RIM OFFSET?

The offset, measured in millimeters, can be negative or positive, and is the distance from the hub-mounting surface to the rim’s true centerline. A positive offset means the hub-mounting surface is closer to the outside edge of the wheel, i.e. the wheel wraps around the hub and brake hardware more deeply; a negative offset means the hub-mounting surface is closer to the inside edge of the wheel and wheel sticks outwards more than inwards.
Negative Offset wheels have their mounting face toward the rear of the wheel – powerful rear-wheel drive cars often have wheels with negative offset. This is the contributing factors of being a bigger “lips” rim.
 When selecting aftermarket wheels, a wheel with too little positive offset will be closer to the fender, and one with too much positive offset will be closer to the suspension components. Wheel width, offset and tire size all determine the way a particular wheel/tire combination will work on a given car.
To maintain handling characteristics and avoid undue loads on bushings and ball joints, the car manufacturer’s original offset should be maintained when choosing new wheels unless there are overriding clearance issues.

Offset also affects the scrub radius of the steering and it is advisable to stay within the limits allowed by the vehicle manufacturer. Because wheel offset changes the lever-arm length between the center of the tire and the centerline of the steering knuckle, the way bumps, road imperfections and acceleration and braking forces are translated to steering torques (bump-steer, torque-steer, etc) will change depending on wheel offset. Likewise, the wheel bearings will see increased thrust loads if the wheel centerline is moved away from the bearing centerline.

WHAT IS CENTERBORE?

The center bore of an alloy wheel is the size of the hole at the back of the wheel which the hub fits into. To help the wheels to seat properly this hole needs to be an exact match to the size of the hub. Please refer to the first picture above this articles.
 Some factory wheels have a centerbore that matches exactly with the hub to reduce vibration by keeping the wheel centered. Wheels with the correct centerbore to the car they will be mounted on are known as hubcentric. Hubcentric wheels take the stress off the lug nuts, reducing the job of the lug nuts to center the wheel to the car.
Wheels that are not hubcentric are known as lugcentric, as the job of centering is done by the lug nuts assuming they are properly torqued down. Centerbore on aftermarket wheels must be equal to or greater than that of the hub or the wheel cannot be mounted on the car. Many aftermarket wheels come with “hubcentric rings” that lock or slide into the back of the wheel to adapt a wheel with a larger centerbore to a smaller hub. These adapters are usually made of plastic but also in aluminium.

Bagaimana pilih / beli sport rim yang betul dan sesuai? Harap artikel di atas dapat membantu.

Hope this information helps you to choose your sport rims properly. =)

Apa yang anda perlu tahu tentang Unmanned aerial vehicle

An unmanned aerial vehicle (UAV), commonly known as a drone and referred to as a Remotely Piloted Aircraft (RPA) by the ICAO, is an aircraft without a human pilot aboard. Its flight is controlled either autonomously by onboard computers or by the remote control of a pilot on the ground or in another vehicle. The typical launch and recovery method of an unmanned aircraft is by the function of an automatic system or an external operator on the ground. Historically, UAVs were simple remotely piloted aircraft, but autonomous control is increasingly being employed.

They are usually deployed for military and special operation applications, but also used in a small but growing number of civil applications, such as policing and firefighting, and nonmilitary security work, such as surveillance of pipelines. UAVs are often preferred for missions that are too "dull, dirty or dangerous" for manned aircraft.

Perlukah DRON dalam perang?

Permintaan global untuk Kenderaan Udara Tanpa Juruterbang (UAV) atau lebih dikenali dengan dron, semakin meningkat ketika pasukan tentera melabur dalam sistem baru bagi meningkatkan keupayaan untuk melakukan pengawasan dan serangan tanpa perlu meletakkan nyawa anggotanya dalam bahaya.

Didorong oleh peningkatan dalam bajet pertahanan, perbelanjaan tahunan global terhadap UAV diramalkan meningkat dua kali ganda daripada AS$5.9 bilion (RM17.7 bilion) kepada AS$11.3 bilion (RM33.9 bilion) pada dekad akan datang, menurut syarikat kaji selidik pertahanan yang berpusat di Amerika Syarikat, Teal Group.

Negara rantau Asia Pasifik adalah pembeli kedua terbesar selepas Amerika Syarikat.

“Hampir semua negara di rantau itu berusaha untuk mendapatkan dron atau membuatnya sendiri. Negara itu termasuk Thailand, India, Singapura, Jepun, Australia, Korea dan sebagainya,” kata Jon Grevatt dari majalah IHS Jane’s Defence Weekly.

Dengan hampir separuh daripada penduduk dunia mendiaminya, Asia juga menjadi kawasan berpotensi mencetuskan peperangan, dari Korea Utara ke Laut China Selatan, Asia Selatan dan Afghanistan.

“UAV sudah menjadi satu keperluan pada era ini jika anda ingin menang dalam peperangan dan pada masa sama jika anda tidak mahu melihat kemalangan jiwa yang terlalu banyak,” kata Ketua Bahagian Dron di Industri Angkasa Lepas Israel (IAI), Tommy Silberring.

IAI yang menjadi perintis pembangunan teknologi UAV untuk tentera Israel pada 1970-an, adalah satu daripada beberapa syarikat pembuat kelengkapan pertahanan yang mempamerkan dron pada Pertunjukan Udara Singapura minggu lalu.

Penggunaan dron berbanding pesawat yang dikendalikan manusia dapat membantu negara yang terbabit dalam peperangan pelbagai hala dan ia lebih diterima orang awam, kata Silberring, bekas pegawai berpangkat kolonel dalam tentera udara Israel.

“Anda sudah pasti tidak mahu memberitahu rakyat negara anda bahawa anda mendedahkan nyawa askar anda untuk sebuah negara lain,” katanya kepada AFP di pertunjukan udara itu.

Dron memainkan peranan penting dalam beberapa konflik terbaru. Amerika Syarikat banyak bergantung kepadanya untuk menyerang sasaran di kawasan yang dikuasai suku kaum di Pakistan yang juga menjadi kubu kuat Taliban dan aktivis al-Qaeda.

Dron Amerika Syarikat juga digunakan dalam campur tangan yang diketuai Nato di Libya tahun lalu.

Menurut IAI, dron yang dikeluarkannya, Heron UAV digunakan oleh 18 pelanggan di seluruh dunia, termasuk Tentera Udara Singapura yang mempamerkan dron miliknya, Heron 1, pada pertunjukan itu.

Heron TP, dron terbesar dalam pasukan tentera Israel dengan rentang sayap sama dengan pesawat penumpang Boeing 737, dipercayai mampu terbang sejauh lebih 7,400 kilometer.

Di Amerika Syarikat, syarikat tempatan seperti General Atomics dan Northrop Grumman dijangka memperoleh faedah daripada rancangan terbaru Pentagon untuk menambah jumlah pesawat yang ada sekarang, iaitu sebanyak 7,494 kepada 30 peratus lagi.

Menurut laporan yang dibentangkannya kepada Kongres pada Januari lalu, tentera Amerika Syarikat dijangka membelanjakan hampir AS$32 bilion (RM96 bilion) untuk UAV baru dalam tempoh lapan tahun akan datang.

“Dalam masa beberapa tahun lagi, kita sudah pasti akan menyaksikan pertumbuhan agresif sistem pesawat tanpa juruterbang digunakan oleh tentera Amerika di seluruh dunia,” kata Komander Robert Moss, pengarah serantau di Pejabat Amerika Syarikat di Institut Kajian Tentera Laut Global.

“UAV boleh digunakan untuk pelbagai tujuan, dari kerja pengawasan, mengumpulkan data atmosfera hingga ke serangan,” katanya.

Permintaan yang meningkat secara mendadak itu mendorong syarikat pembuat di Asia untuk memasuki pasaran yang selama ini dikuasai syarikat Israel dan Amerika Syarikat.

“Kami ingin turut serta dalam industri pesawat tanpa juruterbang tetapi kami bersikap memilih kerana sudah terlalu banyak syarikat terkemuka dalam industri itu,” kata Patrick Choy, Naib Presiden Pasaran Antarabangsa ST Engineering, sebuah syarikat industri pertahanan yang berpusat di Singapura.

ST Engineering melancarkan Skyblade 360, edisi terbaru dalam siri UAV mini pada pertunjukan itu.

Skyblade III, dron yang dikeluarkan sebelum Skyblade 360 digunakan oleh tentera Singapura untuk menyediakan bantuan dari segi pengawasan untuk tentera darat republik itu.

Menurut Choy, ST Engineering tidak berhasrat untuk bersaing dengan syarikat Israel dan Amerika Syarikat bagi membina UAV yang lebih besar.

“Kami mahu membabitkan diri dalam bidang taktikal. Dengan ini kami dapat membantu unit kecil menerusi teknologi UAV kami,” “Anda tidak akan dapat meyakinkan pelanggan untuk membeli UAV yang besar yang memerlukan teknologi bantuan seperti satelit kecuali anda adalah kuasa besar dunia,” katanya.

India juga bersikap sederhana mengenai dronnya, Rustom-1 yang turut menyertai pameran perdagangan itu.

“Keutamaan kami ialah untuk memajukan keupayaan Rustom yang ada sekarang. Kami tidak mempunyai rancangan untuk mengeksportnya,” kata Parimal Kumar, Sibbering tidak bimbang dengan perkembangan syarikat pembuat dron Asia. Dia sebaliknya yakin permintaan terhadap dron Israel akan terus meningkat, “Anda tidak akan dapat bersaing dengan kami. Kami melihat 20 tahun ke depan untuk memastikan kami mempunyai produk yang orang lain tak ada di pasaran,” katanya.

Apa itu special relativity

In physics, special relativity (SR, also known as the special theory of relativity or STR) is the accepted physical theory regarding the relationship between space and time. It is based on two postulates: (1) that the laws of physics are invariant (i.e., identical) in all inertial systems (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source. It was originally proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies".^[1] The inconsistency of classical mechanics with Maxwell’s equations of electromagnetism led to the development of special relativity, which corrects classical mechanics to handle situations involving motions nearing the speed of light. As of today, special relativity is the most accurate model of motion at any speed. Even so, classical mechanics is still useful (due to its simplicity and high accuracy) as an approximation at small velocities relative to the speed of light.

Apa itu Parallel axis theorem

In physics, the parallel axis theorem, also known as Huygens–Steiner theorem after Christiaan Huygens and Jakob Steiner, can be used to determine the mass moment of inertia or the second moment of area of a rigid body about any axis, given the body's moment of inertia about a parallel axis through the object's centre of mass and the perpendicular distance between the axes.

Inertia

Inertia is the resistance of any physical object to any change in its state of motion, including changes to its speed and direction. In other words, it is the tendency of objects to keep moving in a straight line at constant linear velocity. The principle of inertia is one of the fundamental principles of classical physics that are used to describe the motion of objects and how they are affected by applied forces. Inertia comes from the Latin word, iners, meaning idle, sluggish. Inertia is one of the primary manifestations of mass, which is a quantitative property of physical systems. Isaac Newton defined inertia as his first law in his Philosophiæ Naturalis Principia Mathematica, which states:

The vis insita, or innate force of matter, is a power of resisting by which every body, as much as in it lies, endeavours to preserve its present state, whether it be of rest or of moving uniformly forward in a straight line.

In common usage the term "inertia" may refer to an object's "amount of resistance to change in velocity" (which is quantified by its mass), or sometimes to its momentum, depending on the context. The term "inertia" is more properly understood as shorthand for "the principle of inertia" as described by Newton in his First Law of Motion: that an object not subject to any net external force moves at a constant velocity. Thus, an object will continue moving at its current velocity until some force causes its speed or direction to change.

On the surface of the Earth inertia is often masked by the effects of friction and air resistance, both of which tend to decrease the speed of moving objects (commonly to the point of rest), and gravity. This misled classical theorists such as Aristotle, who believed that objects would move only as long as force was applied to them^.

The theory of impetus was an auxiliary or secondary theory of Aristotelian dynamics, put forth initially to explain projectile motion against gravity. It was introduced by John Philoponus in the 6th century and elaborated by Nur ad-Din al-Bitruji at the end of the 12th century, but was only established in western scientific thought by Jean Buridan in the 14th century. It is the intellectual precursor to the concepts of inertia, momentum and acceleration in classical mechanics.

Albert Einstein's theory of Special Relativity, as proposed in his 1905 paper, "On the Electrodynamics of Moving Bodies," was built on the understanding of inertia and inertial reference frames developed by Galileo and Newton.