Very often, our customers ask us what will happen to the wood chipper if you chop the branches more than stated in the specifications. We emphasize that any overloads adversely affect the operation of the equipment, so you should strictly follow the instructions and do not grind more than the branch diameters declared by the manufacturer. Moreover, we do not recommend throwing iron scrap into the grinder.
But there are different cases when working intensively, the operator may accidentally abandon a branch of a larger diameter, or an extraneous metal object may fall. What to do in this case? To remeasure each branch with a tape measure before starting?
To ensure long-term comfortable work with the equipment, and to protect it from accidental overloads, we install special protective mechanisms on all grinders, the main purpose of which is to prevent breakage.
Protective mechanisms vary depending on the type of chipper drive. We propose to consider the principle of protection against overloads of wood chipper ARPAL.
It is recommended to use the ARPAL tractor wood chipper with a cardan shaft equipped with a friction clutch. The principle of operation is to limit the maximum torque transmitted from the tractor power take-off shaft to the branch chopper mechanism. The friction clutch basically consists of friction discs coated with abrasive material. When the torque increases to the moment of operation, the friction discs begin to slip, thereby limiting the transmission of torque. The torque at which the clutch engages is regulated by the clamping of the compression springs, and is individually adjusted for each unit.
The moment of operation of the friction clutch on the tractor wood chippers, you can view in the attached video.
Cardan shafts for powerful models of wood chippers (АМ-160ТР-К, АМ-160ТР) operating from the tractor PTO must additionally be equipped with an overrunning clutch, the purpose of which is to protect the transmission of the grinder and tractor from loads caused by inertial masses. By design, such a coupling resembles a ratchet mechanism (ratchet), which transmits rotation in only one direction, and after the drive shaft stops, the follower continues to rotate freely by inertia.
ARPAL wood chippers with internal combustion engines are also protected by a friction clutch, which performs 3 functions at once:
1. Smooth start of the engine mechanism
2. Protects the mechanism from critical loads
3. Facilitates the release of stuck branches from the hopper.
The clutch consists of cams, which, under the action of centrifugal force during rotation, begin to diverge while being clamped in the pulley body, thereby driving it. When thick branches that have a diameter larger than the mechanism can handle are caught, the engine’s revolutions begin to drop and it becomes insufficient to separate the cams, which must mesh with the clutch housing, which is the drive pulley.
The moment of operation of the friction clutch on the choppers with ICE, see the video.
Electric wood chippers are protected against overloads using the thermal relay mechanism, which is activated as a result of prolonged engine overload and breaks the electric power supply circuit of the chopper.
Therefore, when choosing a wood chipper, be sure to pay attention to whether the equipment you want to purchase is equipped with protective mechanisms. First of all, the durability of the equipment, the convenience and safety of the operator who will work with the machine depend on the availability of such mechanisms.