The drive sprocket and the saw chain behind the spiked bumper shall be guarded to prevent access from both sides and from the top and the rear.Compliance is checked by means of the straight test probe (see Figure 105). It shall not be possible to touch the drive sprocket and the part of the saw chain behind the spiked bumper with the test probe.There may be openings at the front and below the drive sprocket to allow the ejection of wood chips and to adjust the guide bar and saw chain.