Tensioning devices for maintaining tension in chain saws
Tensioning devices for maintaining tension in a chain of a chain saw are disclosed. An example tensioning device includes a housing adapted to be coupled to a drive cog of a chain saw, a saw bar mount adapted to be coupled to a saw bar of a chain saw, and at least one spring adapted to bias the saw bar mount in a distal direction from the housing, thereby tensioning the spring. The tensioning device may also include a ratchet and pawl assembly that allows the saw bar mount to be moved in the distal direction and stops movement of the saw bar mount in a proximal direction. The tensioning device may also include a lock adapted to hold the saw bar mount in a proximal position against a biasing force of the spring. Methods of assembling components for maintaining tension in a chain of a chain saw and of operating the assembled components are also disclosed.
1 . A method of assembling a chain saw cartridge to a tensioning device of a chain saw, the method comprising the steps of:
(i) prior to coupling the chain saw cartridge to the tensioning device, a user of the chain saw manually moving a saw bar mount of the tensioning device in a proximal direction to a cartridge loading position, whereby the user manually moving the saw bar mount in a proximal direction to the cartridge loading position increases a restoring force of at least one spring of the tensioning device;
(ii) while the saw bar mount is in the cartridge loading position, coupling the chain saw cartridge to the tensioning device, wherein the chain saw cartridge includes a saw bar, a drive cog, and a chain around the saw bar and the drive cog, wherein the step of coupling the chain saw cartridge to the tensioning device comprises coupling the saw bar of the chain saw cartridge to the saw bar mount of the tensioning device; and
(iii) releasing the saw bar mount from the cartridge loading position, wherein the restoring force of the at least one spring is adapted to bias the saw bar mount in a distal direction, thereby tensioning the chain of the chain saw cartridge, and wherein the step of releasing the saw bar mount from the cartridge loading position is performed by the user by actuating linear movement of an actuator, which allows the restoring force of the at least one spring to bias the saw bar mount and the saw bar in the distal direction.
2 . The method as recited in claim 1 , further comprising using a lock to temporarily hold the saw bar mount in the cartridge loading position against the restoring force of the at least one spring.
3 . The method as recited in claim 2 , further comprising releasing the lock to perform the step of releasing the saw bar mount from the cartridge loading position.
4 . The method as recited in claim 1 , wherein during use of the chain saw the restoring force of the at least one spring provides a distally-directed force on the saw bar mount that keeps the chain of the chain saw cartridge engaged with the drive cog and with the saw bar and maintains tension in the chain.
5 . The method as recited in claim 4 , further comprising, during use of the chain saw, allowing the saw bar mount to be moved by the at least one spring in the distal direction and stopping movement of the saw bar mount in a proximal direction.
6 . The method as recited in claim 5 , wherein stopping movement of the saw bar mount in the proximal direction is accomplished by a ratchet and pawl assembly.
7 . The method as recited in claim 1 , wherein the saw bar mount comprises one or more pins and the saw bar comprises one or more holes or recesses for receiving the one or more pins of the saw bar mount; and
wherein the step of coupling the chain saw cartridge to the tensioning device comprises coupling the saw bar of the chain saw cartridge to the saw bar mount of the tensioning device by fitting the one or more holes or recesses of the saw bar onto the one or more pins of the saw bar mount.
8 . The method as recited in claim 7 , wherein the saw bar mount comprises one or more pins and the saw bar comprises one or more holes or recesses for receiving the one or more pins of the saw bar mount; and
wherein the step of coupling the chain saw cartridge to the tensioning device comprises coupling the saw bar of the chain saw cartridge to the saw bar mount of the tensioning device by fitting the one or more holes or recesses of the saw bar onto the one or more pins of the saw bar mount.
9 . A method of assembling a chain saw cartridge to a tensioning device of a chain saw, the method comprising the steps of:
(i) prior to coupling the chain saw cartridge to the tensioning device, a user of the chain saw manually moving a saw bar mount of the tensioning device in a proximal direction with respect to a housing of the tensioning device to a cartridge loading position, wherein the saw bar mount comprises at least one post received within at least one channel of the housing, wherein the tensioning device comprises at least one spring located between the saw bar mount and the housing, whereby the user manually moving the saw bar mount in a proximal direction with respect to the housing to the cartridge loading position increases a restoring force of the least one spring of the tensioning device;
(ii) while the saw bar mount is in the cartridge loading position, coupling the chain saw cartridge to the tensioning device, wherein the chain saw cartridge includes a saw bar, a drive cog, and a chain around the saw bar and the drive cog, wherein the step of coupling the chain saw cartridge to the tensioning device comprises coupling the saw bar of the chain saw cartridge to the saw bar mount of the tensioning device; and
(iii) releasing the saw bar mount from the cartridge loading position, wherein the restoring force of the at least one spring is adapted to bias the saw bar mount in a distal direction, thereby tensioning the chain of the chain saw cartridge, and wherein the step of releasing the saw bar mount from the cartridge loading position is performed by the user by actuating linear movement of an actuator, which allows the restoring force of the at least one spring to bias the saw bar mount and the saw bar in the distal direction.
10 . The method as recited in claim 9 , further comprising using a lock to temporarily hold the saw bar mount in the cartridge loading position against the restoring force of the at least one spring.
11 . The method as recited in claim 10 , further comprising releasing the lock to perform the step of releasing the saw bar mount from the cartridge loading position.
12 . The method as recited in claim 9 , wherein during use of the chain saw the restoring force of the at least one spring provides a distally-directed force on the saw bar mount that keeps the chain of the chain saw cartridge engaged with the drive cog and with the saw bar and maintains tension in the chain.
13 . The method as recited in claim 12 , further comprising, during use of the chain saw, allowing the saw bar mount to be moved by the at least one spring in the distal direction and stopping movement of the saw bar mount in a proximal direction.
14 . The method as recited in claim 13 , wherein stopping movement of the saw bar mount in the proximal direction is accomplished by a ratchet and pawl assembly.
15 . The method as recited in claim 9 , wherein the at least one spring of the tensioning device is sleeved around the at least one post of the saw mount.