Bowling machine

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In cricket a bowling machine is a device which enables a batsman to practice (usually in the nets) and to hone specific skills through repetition of the ball being bowled at a certain length, line and speed. It can also be used when there is no-one available to bowl, or no one of the desired style or standard.

Cricket Team sport played with bats and balls

Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a 20-metre (22-yard) pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by striking the ball bowled at the wicket with the bat, while the bowling and fielding side tries to prevent this and dismiss each player. Means of dismissal include being bowled, when the ball hits the stumps and dislodges the bails, and by the fielding side catching the ball after it is hit by the bat, but before it hits the ground. When ten players have been dismissed, the innings ends and the teams swap roles. The game is adjudicated by two umpires, aided by a third umpire and match referee in international matches. They communicate with two off-field scorers who record the match's statistical information.

Cricket nets

A cricket net is a practice net used by batsmen and bowlers to warm up and/or improve their cricketing techniques. Cricket nets consist of a cricket pitch which is enclosed by cricket nets on either side, to the rear and optionally the roof. The bowling end of the net is left open. Cricket nets are the cricket equivalent of baseball's batting cages, though fundamentally different, as baseball cages provide complete ball containment, whereas cricket nets do not.

Bowling (cricket) cricket delivery

Bowling, in cricket, is the action of propelling the ball toward the wicket defended by a batsman. A player skilled at bowling is called a bowler; a bowler who is also a competent batsman is known as an all-rounder. Bowling the ball is distinguished from throwing the ball by a strictly specified biomechanical definition, which restricts the angle of extension of the elbow. A single act of bowling the ball towards the batsman is called a ball or a delivery. Bowlers bowl deliveries in sets of six, called an over. Once a bowler has bowled an over, a teammate will bowl an over from the other end of the pitch. The Laws of Cricket govern how a ball must be bowled. If a ball is bowled illegally, an umpire will rule it a no-ball. If a ball is bowled too wide of the striker for the batsman to be able to play at it with a proper cricket shot, the bowler's end umpire will rule it a wide.

Contents

There are a number of different types of bowling machine available to cricket coaches, each quite different in the ways they achieve the required delivery, though most allow the use of remote control, so that a coach can be closer to a batsman when the stroke is played.

Mechanical bowling machines

This type of machine is by far the most common. It is simple, strong and reliable, as well as being able to bowl a useful range of deliveries.

How they work

The main mechanism of the machine consists of two heavy wheels, between 30 and 50 cm in diameter, fitted with solid or pneumatic rubber tyres, each driven by its own electric motor. These are mounted in a frame such that the wheels are in the same plane, about 7 cm apart (slightly less than the diameter of a cricket ball). A ball joint allows the machine a wide range of movement. The whole assembly is mounted on a sturdy tripod or other frame so that the plane of the wheels is roughly at the height that a typical bowler would release the ball. A chute delivers the ball between the wheels, protecting the coach’s hands.

Electric motor electromechanical device

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of rotation of a shaft. Electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. An electric generator is mechanically identical to an electric motor, but operates in the reverse direction, converting mechanical energy into electrical energy.

Cricket ball hard, solid ball used to play cricket

A cricket ball is a hard, solid ball used to play cricket. A cricket ball consists of cork covered by leather, and manufacture is regulated by cricket law at first-class level. The manipulation of a cricket ball, through employment of its various physical properties, is a staple component of bowling and dismissing batsmen. Movement in the air, and off the ground, is influenced by the condition of the ball, the efforts of the bowler and the pitch, while working on the cricket ball to obtain optimum condition is a key role of the fielding side. The cricket ball is the principal manner through which the batsman scores runs, by manipulating the ball into a position where it would be safe to take a run, or by directing the ball through or over the boundary.

Ball joint

In an automobile, ball joints are spherical bearings that connect the control arms to the steering knuckles. They are used on virtually every automobile made and work similarly to the ball-and-socket design of the human hip joint.

The motors are typically powered by a car battery, and turn in opposite directions. A controller allows variation of the speed of each wheel, allowing the machine to be slowed down for less experienced batsmen, or when the motors are not running at the same speed, swing or spin bowling can be simulated.

These machines will work with any ball of roughly the right size and weight, such as normal cricket balls or tennis balls. However, they usually work best with their own balls, bowling machine balls which are made of hard plastic, and are covered in dimples. These dimples are to help with the swinging characteristics when this type of delivery is desired.

Simulating different deliveries

Fast bowling

This is achieved by setting both wheels to the same speed, as fast as the batsman is able to deal with, although the machine itself would have to be tipped horizontally. The coach can move the machine around slightly to vary the line and length of each ball.

Swing bowling

The plane of the wheels is flat, and the motors are set to run at slightly different speeds. This means the ball will spin about an axis perpendicular to the ground, causing it to swing due to the Magnus effect. If the ball is spinning anticlockwise (looking from above) the ball will swing from right to left; clockwise spin results in a swing from left to right. This means that if the coach slows down the wheel on one side, ball will swing in that direction. The swing produced in this way is different from normal swing bowling, however - it is much more like a curling ball in football.

Magnus effect spinning ball phenomenon

The Magnus effect is an observable phenomenon that is commonly associated with a spinning object moving through a fluid. The path of the spinning object is deflected in a manner that is not present when the object is not spinning. The deflection can be explained by the difference in pressure of the fluid on opposite sides of the spinning object.

Association football Team field sport

Association football, more commonly known as football or soccer, is a team sport played with a spherical ball between two teams of eleven players. It is played by 250 million players in over 200 countries and dependencies, making it the world's most popular sport. The game is played on a rectangular field called a pitch with a goal at each end. The object of the game is to score by moving the ball beyond the goal line into the opposing goal.

Spin bowling

To achieve spin, the machine should be tilted to one side, and the wheels set to different speeds as per swing bowling. It will also probably be necessary to make the machine bowl significantly more slowly. The combined action of the spin imparted by the wheels, and the non-perpendicular axis of that spin will cause the ball to bounce up at an angle. While spinning always see the ball when it has been started to deliver the ball towards the wicket

Seam bowling

This is difficult to achieve since the operator cannot control exactly how the ball will roll into the machine and between the wheels. However, by the law of averages, a ball will occasionally come out with its seam at the correct angle, and bounce unpredictably as a result.

Bouncers

To get balls that bounce unnaturally high or low, the plane of the machine must be set so that it is vertical. Not all machines can do this, simply because their ball joint doesn’t give the required range of movement. To get balls that bounce higher than normal, the lower wheel should spin slightly faster than the upper. Deliveries that bounce much lower than normal are less common and are usually the result of the ball striking a broken-up patch of ground. These balls can still be simulated, however, by increasing the speed of the upper wheel.

Pneumatic bowling machines

This design is significantly less common than the mechanical type and operates using a completely different principle.

How they work

Most of the space in the machine is a hopper that contains the balls. At the bottom of the hopper, near the front, is a rotor with space for six balls. The balls slot into the spaces on the rotor by gravity, which then takes them into the innards of the mechanism. The rotor passes over a trap-door, which the ball opens with its weight, falling into a small chamber.

A pump is used to provide a flow of air into the chamber that the ball drops into. The airflow pushes the ball along the chamber to rubber ring, or gasket, known as a "restrictor". The restrictor has a hole through it that is sightly smaller than the ball, which the ball presses up against. This seals the hole, so air pressure builds up in the chamber. When the pressure is so great that the restrictor can no longer hold it, the ball bursts through, out of the main body of the machine and into an external tube, which guides it upwards and releases it at the height of a bowler's arm.

Simulating different deliveries

Fast bowling

A system exists that allows air to escape from the barrel shortly after it has passed the restrictor. This reduces the pressure on the ball, reducing its muzzle velocity. Closing this increases the speed to its maximum; its maximum speed is 160+ km/hr (100+ mph).

Swing bowling

To do this a curved piece of tubing is attached to the end of the barrel. The ball rolls around this causing it to spin and swing.

Spin bowling

The tubing used for swing bowling can also be used for spin bowling, by pointing the curve somewhere between vertical and horizontal.

Seam bowling

Seam bowling is impossible on this machine as it only accepts tennis balls and cricket training balls such as Slazenger's "Slazball" (a hard, small, low-bounce, heavy ball, similar in appearance to a tennis ball but usually red in colour). Neither of these types of ball has a seam.

Bouncers

The tubing can again be used, this time to simulate high and low bounce by mounting the tube vertically.

Programmable bowling machines

Both of the types of machines described above are fairly simple designs, intended for regular, hard use by clubs, and hence are simple to operate and reliable. They can only simulate one type of delivery with the machine in a given configuration and have other limitations, particularly with spin bowling, which limit their usefulness to players at the highest levels of the game.

Programmable bowling machines are intended to overcome some of these limitations by rapidly re-configuring themselves to bowl different types of delivery in quick succession.

A programmable bowling machine called "Merlyn", which its makers claimed could "bowl any ball known to man" [1] received much public attention when it was used by the English cricket team in the run-up to and during the 2005 Ashes series.

Originally a one-off, Merlyn was built by Henry Pryor, a cricket coach in Herefordshire. Its mechanism has not been publicly revealed, though it is safe to assume it is much more complex than the other machines.

Crucially, the machine was claimed to be able to emulate Shane Warne's leg breaks, and although he is dismissive of its usefulness, [2] the England batsmen disagree, and consider their ability to play spin bowling significantly improved.

The machine, as well as its mechanical abilities, also has significant elements of computer-control built in. It is claimed that it can reproduce an over from a particular bowler if fed the correct data.

One of the more unnerving aspects of the machine is that it provides no indication of the type of ball it is about to bowl until the ball has left the machine. This forces batsmen to work on their instinctive batting, rather than trying to second guess the bowler.

An improved version is currently in development at Loughborough University, which will add visual feedback by showing a representation of the bowler projected onto a screen. The ball will be released as the virtual bowler’s hand reaches the hole from which the ball is released. This version of the machine is intended for mass production, so it can be sold to cricket clubs around the world. [3] In the winter of 2009/10 the ECB acquired 20 of the machines, one for each county and two for the performance centre at Loughborough. [4]

See also

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References

  1. ↑ The history page at Merlyn’s Official Website Archived 6 July 2006 at the Wayback Machine
  2. ↑ "Defeat will make England hungry – Warne" by Jenny Thompson Cricinfo, 7 June 2006 retrieved 21 July 2006
  3. ↑ "England await Merlyn's heir" by Pranav Soneji, BBC, 5 June 2006, retrieved 21 July 2006
  4. ↑ http://www.cricinfo.com/england/content/current/story/439374.html
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