According to the safety regulations, handwheels must be secured to the shafts in such a way that during mechanical drive they do not rotate. These safety handwheels comply with this requirement.
Procedure: By axial displacement of the wheel (pushing or pulling) a set of mating internal and external serrated gear teeth are engaged. The wheel is now positively engaged to the shaft. When the wheel is released, it automatically disengages.
The clutch components are assembled together in an enclosed unit – the clutch mechanism. This clutch mechanism is constructed so that it may be easily attached to all current types of handwheels and other machine parts. For further details of clutch mechanisms, see GN 000.4 and GN 000.5.
The same handwheel and clutch mechanism can be arranged to require either a pushing or pulling action to engage. Greater protection against an accident is provided by the ‘pulling’ arrangement; the wheel cannot be engaged by inadvertent pressure.
Our standard Safety Handwheels are available in aluminum, with a keyway, and with or without revolving handle.
Originally intended for only a limited range of applications, safety clutch handwheels are now applied to an extremely wide range of machines and equipment. In order to ensure the utmost security against accidents, the following guidelines are offered; we can, however, not accept any liability for any possible consequential damage, which may be caused through the use of our clutch mechanisms.
1. Handwheels with friction bearing (clutch mechanism GN 000.4)
Model D (with revolving handle)
The range of application of these handwheels is limited to relatively low shaft velocities or higher velocities of only short duration (e.g. lead-screws for milling machines with fast traverse speed). A very high risk of pollution (grinding dust) can limit its scope still further.
Should the declutched handwheel be put deliberately into motion in the same direction as the revolving shaft, the handwheel will tend to turn continuously due to bearing friction. At higher handwheel speeds, this could lead to vibration caused by the rotating mass of the handle and create a certain danger.
Model A (without revolving handle)
Due to the absence of a handle, admittedly this gives these wheels a tendency to turn, but this does not create any danger because minimal contact holds them stationary. For this reason, these safety wheels can be used with appreciably higher speeds. The bearing load is negligible. At high velocity, however, the unbalanced handwheel could cause vibration.
Lubrication at regular intervals is in every case a pre-requisite for troublefree functioning of the friction bearing clutch mechanisms.
2. Safety Handwheels with needle bearings (clutch mechanism GN 000.5)
In principle, the details specified under paragraph 1 will also apply to these safety handwheels.
The needle bearings offer a great advantage over friction bearings through lower friction, and they are less prone to break down through lack of lubrication at higher velocities.
The increased bearing length and lower friction (bearing surface is hardened), as well as the finer teeth, make it in addition easier to declutch the handwheels.