Tree trimming apparatus and method

An apparatus and method for removing the tops of trees, the apparatus including a rotatable first boom configured for coupling to and extending vertically downward from an aircraft and a cutting assembly hingedly coupled to a bottom end portion of the first boom. The cutting assembly includes a housing containing a motor, the housing having an upper portion coupled to the bottom end portion of the first boom. A second boom extends from a lower portion of the housing and supports thereon a singular circular saw which is operatively coupled to the motor. The second boom is arranged at an angle of about 30° to about 55° relative to the first boom. This accomplished by including bend within the housing.

FIELD OF THE INVENTION

The present invention is directed to an apparatus and method for trimming vegetation, and more particularly, to a method for removing the tops of trees by cutting the tree tops with a saw suspended from an aircraft.

BACKGROUND OF THE INVENTION

Aerial saws for trimming vegetation are known in the art. For example, U.S. Pat. No. 4,554,781 discloses a tree trimmer apparatus including a boom hanging vertically downward from a helicopter and carrying a plurality of circular saws arranged with their blades nearly adjacent over a length of the boom. The boom is attached to the helicopter in a manner that prevents rotation about a vertical axis while allowing rotational movement about a horizontal axis at right angles to the normal direction of motion of the helicopter. The blades are powered by a hydraulic motor with hydraulic fluid under pressure from a pump in the helicopter.

U.S. Pat. No. 4,815,263 discloses an airborne tree trimming apparatus including a boom extension vertically suspended from a helicopter and a plurality of circular saw blades arranged in a tandem, coplanar relationship on an operating boom which is attached to the boom extension by means of a boom pivot. The circular saw blades rotate about parallel, substantially horizontal axes which are oriented substantially at right angles to the normal direction of motion of the helicopter and are belt-driven by an internal combustion engine which is mounted on the operating boom, above the circular saw blades.

U.S. Pat. No. 5,961,070 discloses an aerial chain saw suspended from a helicopter by a non-rigid suspension system. A continuous chain extends around a chain saw bar, driven by a sprocket. Hydraulic lines to and from the helicopter provide hydraulic power to a hydraulic motor mounted at the upper end of the bar.

SUMMARY OF THE INVENTION

The present invention is directed to an apparatus and method for removing the tops of trees with a saw suspended from an aircraft. According to one aspect of the invention there is provided a tree trimming apparatus including a rotatable first boom configured for coupling to and extending vertically downward from an aircraft and a cutting assembly hingedly coupled to a bottom end portion of the first boom. The cutting assembly includes a housing containing a motor, the housing having an upper portion coupled to the bottom end portion of the first boom. A second boom extends from a lower portion of the housing and supports thereon a circular saw which is operatively coupled to the motor. The second boom is arranged at an angle of about 30° to about 55° relative to the first boom. This accomplished by including bend within the housing. In particular, the housing includes a front wall, a rear wall and opposing lateral walls connecting the front and rear walls together, the front and rear walls each including a bend forming an angle of about 30° to about 55°.

In use, the apparatus is suspended from a helicopter and transported to a tree to be trimmed. When in transit, the first boom is maintained in a first position with the second boom extending away from a forward direction of travel of the helicopter. This arrangement is more aerodynamic than having the second boom extending laterally or forward relative to the direction of travel of the helicopter. As the helicopter approaches the tree, the first boom is rotated into a second position with the second boom extending laterally from the forward direction of travel of the helicopter. This arrangement of the second boom allows the helicopter pilot to more easily view the tree to be trimmed and engagement of the circular saw with the tree than if the second boom extended toward the front or rear of the helicopter. As the apparatus is moved towards the tree, a bottom end portion of the second boom, which extend below a lower edge of the circular saw is used to guide the saw towards the tree top so that the saw may engage and cut the tree top.

According to another aspect of the invention there is provided a tree trimming apparatus including a first boom portion extending vertically downward from a helicopter, a second boom portion coupled to and suspended from the first boom portion, the second boom portion being arranged at about a 40° angle to about a 50° angle to the first boom portion, and a cutting member supported by the second boom portion. A housing containing a power source operatively coupled to the cutting member is coupled to and between the first boom portion and the second boom portion. In particular, a hinge joint operatively couples the first boom portion to the housing, which in turn, is rigidly coupled to the second boom portion.

According to yet another aspect of the invention, there is provided a tree trimming apparatus including a flexible first boom rotatably coupled to and extending vertically downward from an aircraft, housing containing a fuel tank and a motor operatively coupled to the fuel tank, the housing having an upper portion hingedly coupled to the bottom end portion of the first boom, a rigid second boom rigidly coupled to and extending downwardly from the housing, and a circular saw operatively coupled to the motor and supported by the second boom. To assist the aircraft pilot with engaging the tree top and preventing pinching of the saw blade as it cuts through a tree top, the second boom is arranged at an angle of about 45° relative to the first boom and includes a guide portion extending below a lower edge of the circular saw. In use, the apparatus is positioned above a tree and the guide portion of the second boom is engaged with a tree top for guiding the circular saw towards the tree top.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is directed to a tree trimming system for cutting or removing the tops of trees. As depicted inFIG. 1, the system generally includes an aircraft such as a helicopter10, a first boom12coupled to and extending vertically underneath helicopter10and a cutting assembly14, the cutting assembly consisting of a motor housing16, a second boom18and a circular saw20, the circular saw and the second boom being arranged at a desired angle relative to first boom12. In use, helicopter10is positioned over a tree11with first boom12rotated so that second boom18extends laterally relative to helicopter10. As cutting assembly14is moved towards tree11, a guide portion22formed by a bottom end portion of second boom18is used by the helicopter pilot to guide saw20towards the tree top so that the saw may engage and cut the tree top.

Referring toFIG. 1, the underside of helicopter10is fitted with a hook motor24having a rotatable shaft extending downwardly therefrom and terminating in a hook26. Suspended from hook26is first boom12. First boom12may be constructed from a fifty foot, approximately three inch diameter aluminum pipe. The length of first boom12can be greater, for example, if the tree tops to be cut are adjacent to structures that are taller than the trees such as power lines or towers. Rigidly coupled to the upper end of first boom12is a loop28through which hook26is secured. The attachment of loop28to hook26allows the pilot to selectively rotate first boom12in either direction by remotely activating hook motor24. It is contemplated that a redundant hooking system may be used to secure and suspend first boom12from helicopter10. Such a system may include, in addition to hook26, a chain coupled to and been first boom12and helicopter10or hook26. It is also contemplated that a hooking system may be implemented giving the pilot the option of remotely releasing first boom12from helicopter10in an emergency, for example, if saw20or guide portion22becomes entangled in a tree or power line. Such a system may include means for detaching hook motor24from the underside of helicopter10or releasing hook26from hook motor24.

Referring toFIG. 2, located at the bottom end of first boom12is a bracket30rigidly coupled thereto. Bracket30is configured for hingedly coupling first boom12to cutting assembly14. Bracket30includes opposing arms32which, in part, define a slot34. Integrally formed with the top end of motor cage14is a cylinder36. Cylinder36is configured for being received within slot30and secured between opposing arms32by a pin38. In particular, pin38extends to and between opposing arms32and is securely fixed there between. Arranged in this manner, cylinder36and cutting assembly14are free to rotate about pin38.

As illustrated inFIG. 2, the rotational axis defined by rotation of cylinder36about pin38is not arranged perpendicularly to the rotational axis of first boom12. Rather, the rotational axes are tilted relative to one another. As explained below, the angle formed by the intersection of rotational axes about pin38and first boom12, in combination with the design of motor cage14, ensures that a plane formed by saw20intersects first boom12or the rotational axis thereof at about a 135° angle. This way, when in use, saw20can engage a vertically extending branch or top of tree11at an angle of about 45°, which increases the cutting efficiency of the saw20while decreasing pinching of saw20by the vertically extending portion of the tree during cutting.

More particularly, as depicted inFIGS. 2 through 5, motor cage16includes a first wall40forming a first face, a second wall42forming a second face and a pair of opposing side walls coupling first and second walls40,42together to form an enclosure. The enclosure has an upper portion44having a generally conical or pyramid shape terminating at the upper end thereof at cylinder36, a middle portion46having a generally rectangular shape and a lower portion48having a generally half-conical or half-pyramid shape. Upper portion44is arranged at angle relative to middle portion46with first and second walls40,42forming complimentary bends. The angles formed between the upper and middle portions44,46by the bends, in combination with the angle formed between the rotational axes of first boom12and cylinder36about pin38, are configured to make sure saw20is maintained at an angle of about 45° relative to tree11during cutting.

Referring toFIGS. 3 through 5, the lower end of lower portion48of motor cage16terminates in a rectangular sleeve50. Sleeve50defines an opening into which an upper end of second boom18is rigidly secured by bolts or the like. AS best illustrated inFIG. 3, first face of first wall4is essentially coplanar with the face of second boom18from which saw20extends. Second boom18is constructed of rectangular steel tubing having a length of about 11′. Located about 4 feet from the lower end of second boom is a saw connection bracket52for rotatably securing saw20to second boom18. That portion of the lower end of second boom18that extends downwardly from a periphery21of saw20is referred to as the guide portion22.

Referring toFIG. 6, saw20is operatively coupled to a saw motor54contained within motor cage16by a continuous belt56. Belt56engages a wheel that is rotatably coupled to a drive shaft of the motor. Belt56extends downwardly through hollow second boom18and engages a wheel that is operatively coupled to a saw shaft60. Upon rotation of saw shaft60, saw20is caused to rotate. Fuel for saw motor54is stored in tank58, which is also contained within motor cage16.

When in use, cutting assembly14is coupled to first boom12as described above and suspended underneath helicopter10. During transport to a worksite, first boom12is rotated such that second boom18is aligned with the forward direction of travel of the helicopter, with the second boom trailing behind motor cage16. Trailing second boom18behind motor cage16minimizes the amount of drag created by the cutting assembly as it is moved through the air.

Referring toFIGS. 1, 7 and 8, once helicopter10reaches the worksite, the pilot remotely activates hook motor24and thereby rotates first boom1290° so that second boom18extends out laterally relative to the helicopter. This is done so that the pilot can see saw20. The pilot then remotely activates saw motor54causing saw20to rotate. The pilot moves saw20towards tree11until guide portion22of second boom18contacts tree11. With guide portion22pressing against tree11, the pilot moves saw20toward tree11so that saw20may engage and cut tree11. When engaged with tree11, saw20will form an angle A of about 45° relative to tree11and an angle B of about 135° relative to first boom12. By engaging tree11at a 45° with saw20, the tree is less likely to pinch saw20and thereby hinder cutting than if saw20were arranged at about a 90° angle to tree11. Following cutting of tree11, the pilot remotely deactivates saw motor54and activates hook motor24for rotating second boom18back into the transport position.

As will be understood by those familiar with the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosures and description herein are intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims.