Chain saw for branch cutting

The invention concerns a tool for cutting branches with diameters of up to 200 mm and above. High branches may be cut by fitting a telescopic extension piece. The cutting of branches is easy and safe with this tool. The tool is designed in such a way that if any parts become unloosened the bracket will not release itself from the bevel gear pair and the tool will therefore not fall, which is the most dangerous of all possible occurrences. The safety of the tool is also guaranteed by the semi-truncated bell-shaped element which ensures that the same protection is provided by means of the ring nut which, once tightened, is blocked with a safety rod. The tool therefore guarantees a very high level of safety, which is an absolute requirement for compliance with EU regulations.

The invention falls within the technical field of human requirements and within the application field of instrument and tool manufacturing. The tool may be easily used either during professional activities or for hobby purposes.

It may used directly by the operator or fixed to a rod fitted with a bevel gear pair to which the DC or AC driving power is provided by an internal combustion engine. It has been rationally designed and the manufacture and maintenance is easy. An interesting point is that, as shown in more detail below, the parts from which it is formed - such as oil tank, pump, filters, positioning washer, collar or bell-shaped bracket, oil sump, blade and chain etc are easily and rapidly removed and replaced.

This invention is more easily operated and maintained than previous solutions as a result of the above-mentioned ease which parts may be removed and replaced.

The invention is described below, where reference is made to the current version and the following drawings, which are attached herewith: <ul id="ul0001" list-style="none" compact="compact"><li>Fig. 1 Schematic diagram of tool</li><li>Fig. 2 Sectional view of self-priming pump</li><li>Fig. 3 Side view of self-priming pump</li><li>Fig. 4 Schematic sectional view of tool</li><li>Fig. 5 Schematic exploded view of tool</li><li>Fig. 6 Detail of clamp and truncated cone</li><li>Fig. 7 Positioning washer: a) bottom view; b) side view; c) top view.</li></ul>

This tool is use for cutting branches. It is formed by a main body, a self-priming pump, a joint, a positioning washer, a collar bracket, an oil sump, hook supports, stud inserts, etc. Main body 1 holds bearing 27 which has the role of holding the transmission axis 4, an oil tank 16 which contains the chain lubrication oil, two or more inserts 14 which are necessary to fix the oil sump and the blade, a pump 19 to send the oil from the tank to the inlet at the chain, an oil filter 18, a transmission axis 4 to run on the bearing 27, a joint 22, a pre-loading spring 2 for the bevel gear pair, a positioning washer 21, a pre-loading screw for a pre-loading spring 25 and another screw 26 to fix the bracket 20 to the collar, a bevel gear pair 23, a cam 3, an adjustment washer 6 and a transmission reel 5, a ring seal 29, two studs 12, four or more fixing screws 13, a plug with gasket 16 for the tank 17, a ring seal 15, a protection sump 7, two bushes 10 for nut support, a screw 11 to regulate the chain blade, a chain-tensioning pin 9, two self-blocking nuts 8.

A low profile chain runs around the blade 30. The main body 1 is fitted with an inlet hole 51 for the passage of oil, a discharge hole 52, and an air inlet hole 53 to the tank.

The self-priming pump is without doubt an original aspect of the invention. It has been specifically designed for use in the tool in question and is formed by a main body 31, a plug 32 for pipe 35 for oil suction, a pipe 33 for oil discharge, a plug 34, a cap 36 for contact with the cam, a piston 37 for oil pumping, a valve formed by a spring 38 and a ring seal 39, a calibrated hole for oil suction, hole 41 to fix the pump screws, a sintered filter 42 for suction of air from the tank, a check valve 43 to reset the air circuit, a hole 44 for oil discharge, a pump cylinder 45, a piston return spring 46.

Joint 22 which fits in shaft 4 is replaceable with others depending on the power takeoff which is used.

Positioning washer 21 is formed by position 47 for the angular positioning of the tool, a blocking device 48, spoked elements 49. It is fitted with air inlet holes 50. The bracket 20 may also be replaced by a semi-truncated bell-shaped element 51 Fig. 6, fitted with ring nut 52 in which a threaded rod is fitted 53 which ends with a washer 54 covered with a layer of anti-slip rubber. The hook supports 55 fitted to the main body 1 are asymmetric in order to make it easier to determine the side on which the cut must be made.

The stud inserts 14 allow the immediate replacement of the studs if they are worn.