Ball Arm

The ball arm is the piece that contains the accelerometer and allows the headform to rotate.


The Ball Arm is the piece that contains the accelerometer that calculates the speed of the impact. It is locked in place between the clamp and the head form.


The Ball Arm has been custom designed for our helmet testing machines. If you desire a custom design for use with another machine please provide the following information with your order.

The angularity of the arm refers to the drawing measurement C. The different angles most commonly used are 20°, 25°, 30°and 35°. The length of the arm refers to the drawing measurement A. The diameter of the arm refers to the drawing measurement B. Material requested (see below).

The ball arm can be made of three different types of materials to reach different weights depending upon the configuration of your drop assembly.

Description	A	E	J	M	O	Spherical-Impactor
Head Form size	1820	2415	3100	3130	3200	3100
Clamp	758	1173	488	458	388	488
4 bolts	82	82	82	82	82	82
Accelerometer kit	10	10	10	10	10	10
Drop Follower / Flying arm	730	730	730	730	730	730
Aluminum Ball arm	0	590	590	590	590	590
Stainless steel Ball arm	1600	0	0	0	0	0
Magnesium Ball arm	0	0	0	0	0	0

Total	5000	5000	5000	5000	5000	5000
Standard Request(total drop mass)	5.0±0.1	5.0±0.1	5.0±0.1	5.0±0.1	5.0±0.1	5.0±0.1

4 bolts: Are used to secure the clamp to the head form.
Only 5/16 NC 18 - 1 3/4 inch length bolts should be used to avoid any damage to the tread in the head form.
Accelerometer kit: Consists of the accelerometer sensor, support bed, cable.
Drop Carriage / Flying arm: The drop guiding system on the machine that will maintain the head form and other parts of the drop assembly in the trajectory of the impact.
Ball Arm: The Ball Arm contains the accelerometer sensor and is the moving joint connected to the head form. It allows for various positioning of the head form.