Various types of vibrator are used on site. The poker, or immersion vibrator, is the most popular as it works directly on the concrete and can be moved around easily. Two types are available. In the most common the head containing the vibratory mechanism is separate from the motor (petrol or electric), to which it is connected by a flexible drive shaft.
The second type has the motor and vibratory mechanism in the same head. Power is by compressed air or a dedicated electrical supply. Pokers with diameters ranging from 25 to 75 mm are readily available; choice of the appropriate size will depend on the arrangement of the reinforcement in the pour.