NZ789597A

NZ789597A - Saw Apparatus with Hydraulic Tensioning

Info

Publication number: NZ789597A
Application number: NZ789597A
Authority: NZ
Inventors: howorth James; Boys Michael
Original assignee: Deere & Company
Filing date: 2022-06-21
Publication date: 2022-07-01

Abstract

saw apparatus includes a guide bar, a chain driver, and an endless cutting chain trained about the guide bar and the chain driver. A hydraulic chain tensioning apparatus has a hydraulic actuator configured to be driven by a hydraulic power source to act against the guide bar to maintain tension in the cutting chain. A tension release valve is provided between the hydraulic power source and the hydraulic actuator. The tension release valve has a check valve, and a manual override press-button configured to maintain the check valve in an open condition while depressed. The tension release valve has a spring detent configured to maintain the manual override press-button in a depressed condition until selectively released. the cutting chain. A tension release valve is provided between the hydraulic power source and the hydraulic actuator. The tension release valve has a check valve, and a manual override press-button configured to maintain the check valve in an open condition while depressed. The tension release valve has a spring detent configured to maintain the manual override press-button in a depressed condition until selectively released.

Claims

1. A saw apparatus including: a guide bar; a chain driver; an endless cutting chain trained about the guide bar and the chain driver; a hydraulic chain tensioning apparatus, including: a hydraulic actuator configured to be driven by a hydraulic power source to act against the guide bar to maintain tension in the cutting chain; a tension release valve between the hydraulic power source and the hydraulic actuator, n the n release valve includes: a check valve; a manual override press-button configured to in the check valve in an open condition while depressed, wherein the tension release valve includes a spring detent ured to maintain the manual override press-button in a depressed condition until selectively released.

2. The saw apparatus of claim 1, wherein the check valve includes a check valve closing member configured to be moveable ve to a valve seat, and the tension release valve includes a button shaft extending from the press-button, such that in use the button shaft acts against the check valve g member when the press-button is depressed in order to drive the check valve closing member off the valve seat.

3. The saw tus of claim 2, wherein the check valve closing member includes a longitudinal bore having a narrow portion at an end proximal the button shaft, and an internal ball provided within the longitudinal bore, held proximal the narrow portion by a retention feature.

4. The saw apparatus of claim 3, wherein the check valve closing member is configured such that the internal ball has limited nt between a seated position against the narrow portion and a ed position against the ion pin.

5. The saw apparatus of claim 3, wherein the button shaft includes a drive pin configured to be received in the narrow portion, wherein the drive pin extends in a longitudinal direction beyond a bearing surface of the button shaft configured to act against the check valve closing member in use. 316777

6. The saw apparatus of claim 5, wherein the tension release valve is ured such that the drive pin acts against the internal ball before the bearing surface of the button shaft acts against the check valve closing member when the press-button is depressed.

7. The saw apparatus of claim 1, wherein the tension release valve includes a check valve body including an inner bore in which the check valve is ed, and at least one channel on an exterior surface of the check valve body.

8. The saw apparatus of claim 7, wherein the check valve body is received in a recess having a base surface acting as a valve seat, the base surface having a port in fluid communication with the hydraulic actuator.

9. The saw apparatus of claim 8, wherein at least one spring biases the check valve body towards the base surface.

10. The saw apparatus of claim 9, wherein the tension release valve is configured such that when re at the port exceeds a second predetermined threshold the check valve body is lifted from the base surface to permit fluid flow through the at least one channel on the exterior surface of the check valve body.

11. A timber-working , including: a frame, a saw apparatus mounted to the frame, wherein the saw apparatus includes: a guide bar; a chain driver; an endless g chain trained about the guide bar and the chain driver; a hydraulic chain tensioning apparatus, including: a hydraulic actuator configured to be driven by a hydraulic power source to act t the guide bar to maintain tension in the cutting chain; a tension e valve between the hydraulic power source and the hydraulic actuator, n the tension release valve includes: a check valve; a manual override press-button configured to maintain the check 316777 valve in an open condition while depressed, wherein the tension release valve es a spring detent configured to maintain the manual override press-button in a depressed condition until selectively released.

12. The timber-working device of claim 11, including at least one pair of arms lly attached to the frame and configured to be controlled to grasp at least one tree stem.

13. The timber-working device of claim 12, including a feed mechanism configured to feed the at least one stem relative to the frame. 12 14 .1 F I G 16 30 18 28 10 20 24 40 26 210 204 . 2 F I G 202 206 208 300 200 324 300 312 308 222 240 314 304 320 300 330 306 322 324 350 300 330 360 356 358 330 350 350 300