Bowling Terminology
Armadillo - Clear plastic device for determining a bowler's positive axis point. This device has a series of lines on it, which get matched up to a bowler's initial track. When the device is aligned with the ball track, the device points to the bowler's axis point.
Axis of rotation - (example, 0, 45, and 90 degrees) This is a measure of the direction of the initial rotation on the ball with respect to the lane. It is a measurement of the angle between the initial spin axis and the foul line running across the lane. A zero degree axis of rotation is all forward roll. The rotation on the ball is in the direction of the forward travel. The rotation will help keep the ball in the initial direction. The ball will not hook very much. It will roll out early. Therefore, a bowler with this style will need balls drilled to go long.
A 90-degree axis of rotation is all side roll. The rotation is perpendicular to the initial direction. The rotation is trying to make the ball hook at a 90-degree angle to the initial direction. This gives the ball more potential to hook. This style causes the ball to skid further down the lane and then hook more. A bowler with this style will most likely need balls drilled to hook earlier, such as, axis weight or pins closer to their axis.
Axis tilt - (example, a spinner versus a full roller) This is a measure of the angle of the initial spin axis to a horizontal plane. A full roller or high track style would have little or no axis tilt. The initial spin axis would be parallel or close to parallel with the lane surface. One rotation of the ball would cover the major diameter of the ball. A spinner would have an initial spin axis tilted up from the lane. The ball track would be far away from the thumb and finger holes. One rotation of the ball would cover a much smaller diameter than other bowlers. The spinner style will get the ball further down the lane before it hooks.
Axis weight - Axis weight is a drilling pattern designed to produce little or no track flare and get the ball into an early roll with little backend reaction. Axis weight has the pin located on or near the bowler's PAP. The core is positioned along the initial spin axis. This places the core in a stable position. The ball will be initially rotating about the minimum RG axis, which is a stable core position. Therefore, it will continue to rotate about this axis creating no track flare. This reduces the backend reaction. Since the ball is rotating about the low RG axis, it is easier for the bowler to rotate it off their hand, which gets the ball into an earlier roll.
Backend - This is the area of the lane closest to the pin deck. It is approximately the last 20-25 feet of the lane. This is the area of the lane that is not oiled. The oil can move to the backend of the lane due to bowling activity, which is referred to as "no backends". "Strong backends" are lanes that hook a lot in the last 20 feet.
Balance Hole - (or weight hole) This is an extra hole in a ball which is used to get the ball within ABC specifications for imbalance (static balance). The maximum allowable diameter is 1-1/4" for ABC and 1-3/8" for PBA.
Break point - The location of the ball path which is closest to the gutter. Low RG balls have a sooner break point and high RG balls have a later break point.
CATS™ - This stands for Computer Aided Tracking System™. It is a device for measuring the path of the ball on the lane. It measures the position of the ball at different locations down the lane, the angle of travel, the velocity and the friction (COF).
Center of gravity (Cg) - The center of gravity is the location of the heaviest point on a ball. It is marked on the surface of the ball. The true Cg is only a few hundredths of an inch from the center of the ball. But, a line drawn from the actual center of the ball through the Cg would extend to the surface of the ball at the Cg mark. This designed-in imbalance effects the ball path slightly. The imbalance makes the ball want to curve in the direction of the imbalance.
900 Global balls which have a symmetric cores are marked by a pin prick with the 900 Global logo engraved over it. 900 Global balls with an asymmetric cores are marked by a pin prick and then a circle inside a circle, which is engraved on the ball.
Christmas Tree Condition - This refers to a type of oiling pattern applied to the lanes. The oiling pattern looks like a Christmas tree lying on the lane. There is oil applied from gutter to gutter at the foul line and then it tapers to a point in the middle of the lane at the end of the oil, which is about 36-40 feet from the foul line. The goal of this oil pattern was to allow bowlers to play anywhere on the lane because there was oil across the lane at the foul line and less on the outside boards.
Differential RG - This is the difference between the minimum and maximum RG axis in a ball. This property determines the track flare potential. The maximum allowable differential RG is 0.080 inches. The more the differential RG, the more potential for track flare. Track flare increases the friction between the ball and the lane.
Durometer - This is a gage for measuring the hardness of a ball. ABC requires a minimum hardness of 72 durometer D. PBA has a minimum hardness specification of 75.
Full roller - This is a bowling style where the ball will track between the finger and thumbhole.
Heads - This is the front part of the lane. Also called the maple area of the lane because of the material from which it is made.
High RG drilling - This is a drilling pattern where the pin is located at approximately 90 degrees (or 6 to 6-3/4 inches) to the PAP. It is called this because the core is initially rotating around its highest RG axis off the bowler's hand. This results in the ball skidding further down the lane before hooking. The pin may be positioned close to or in the bowler's track.
Hook out - This is when the path of the ball has completed hooking and starts to travel in a straight line. The stages of the ball path are described as skid, hook and roll. After the ball skids on the oil and hooks on the dry backend, it will eventually start to just roll. This is hook out, and used to be called roll out.
Leverage drilling - This is a drilling pattern that produces the maximum amount of track flare. The pin and CG are located at 3-3/8" from the bowler's PAP, which places the core at a 45-degree angle to the axis line. This is an unstable position for a dynamic core. The core wants to move away from this location, causing track flare. The track flare increases the friction between the ball and lane, which gets the ball into an early roll. Depending on the bowler's style, the added friction can sometime increase the sharpness of the turn at the break point (especially for low RPM bowlers); or for others (especially higher RPM bowlers), it can cause the ball to slow down too much in the oil. This uses up the energy in the oil where the ball cannot hook very easily and reduces the turn at the break point.
Mica - Technically, a rock material. It is added to balls to pearlize them. Pearlized balls normally skid further and then snap harder. Some new types (sizes) of mica are being added to balls to effect their performance. Some actually help a ball to roll earlier, increasing the arc at the break point.
Mid line - This is a terminology used on drill sheets. It is the horizontal line that extends from the center of the grip at 90 degrees to the grip centerline.
Mid plane - This is a terminology used on drill sheets. It is also called the vertical axis line. It is the line that runs vertically through the PAP.
Moment of inertia - This, by definition, is the resistance to rotating motion. Mathematically, it is equal to the mass times the distance squared. The further the mass is away from the rotation point, the harder it is to rotate (or to slow down). It is interchangeable with radius of gyration as far as its effect on the ball reaction.
Pin in - This is a ball that has the pin and center of gravity within 1 inch of each other.
Pin out - This is a ball that has the pin and CG greater then 2" from each other.
Positive axis point (PAP) - This is the point on a ball that it wants to initially rotate about when a bowler releases it. The bowler's style determines this location. It is measured from the center of the grip over a distance along the midline and up a distance along the mid plane (vertical axis line).
Quarter scale - A tool used to layout a ball. It covers a quarter of the ball and has a straight edge with a scale to indicate inches. It is used to measures the span and mark it on the ball.
Radius of gyration (Rg) - This is a measurement of the effective weight distribution in a ball. It relates to the moment of inertia of the ball. It is a value which measures the resistance to rotational motion. It is equal to the square root of the moment of inertia divided by the weight. The higher the Rg the more the weight is moved out towards the shell of the ball, which makes it harder to rotate (or spin). This delays the hook until further down the lane. A low Rg ball has the weight located closer to the center of the ball. This makes it easier to rotate and creates an earlier hooking motion or break point.
Reverse Block - A lane condition pattern with more oil on the outside boards then on the middle boards. This makes for a low scoring condition. The ball will not hook on the outside boards because of the heavy oil, and it will hook too much on the middle boards because of the reduced amount of oil.
Spinner - This a style of bowling referring to how a bowler releases a ball. The bowler's wrist rotates around the top of the ball at release causing the ball to spin down the lane (similar to a top). The axis is tilted up in the air and the track is small and far away from the gripping holes. This style helps to get the ball down the lane before it hooks.
Top Hat - See "Walled Condition".
"Tube" Shot - A lane condition with a lot of oil from gutter to gutter but with a few adjoining boards with less oil. The best way to place this condition is to throw the ball on these drier boards, or "Tube". This results in all bowlers playing the same area of the lane.
Track flare - This is the movement of the ball track on a ball caused by the differential RG designed into a ball. See differential RG.
Vertical axis line - See "Mid plane".
Walled Condition - This is also called "Top Hat" or "blocked lanes". This refers to a lane condition that makes it easy to score high. The oil is applied with a light coat on the outside boards on both sides of the lane (approximately the outside ten boards). Then the amount of oil increases abruptly with a lot of oil in the middle of the lane. This large change in the oil amount is called a "wall" or a "Top Hat" oil pattern. The ball will hook a lot when it is rolled on the outside drier boards and will hook very little when it is rolled on the heavy oil in the middle of the lane. This will result in errant shots ending up in the strike pocket because the ball will follow the "wall" to the strike pocket.
