Depth control for endless chain type trencher

• US 4,050,171 A
• Filed: 05/12/1976
• Issued: 09/27/1977
• Est. Priority Date: 05/12/1976
• Status: Expired due to Term

• Current Assignee: Spectra Physics LaserPlane Inc (Trimble Inc.)
• Original Assignee: Laserplane Corporation
• Inventors: Teach, Ted L.
• Primary Examiner(s): Crowder, Clifford D.
• Application Number:
  US05/685,528
• Time in Patent Office: 503 Days
• Field of Search: 37/DIG. 19, 37/DIG. 20, 37/DIG. 1, 37/86, 37/90, 172/4, 172/4.5, 172/430
• US Class Current: 37/348
• CPC Class Codes: E02F 5/06 with digging elements mounted on an endless chain E02F5/109 takes precedence; with digging elements mounted on an endless chain per se E02F3/08
• CPC Class Codes: E02F 5/145 control and indicating devices

Abstract

The cutting depth of an endless chain type trencher is normally determined by the angle of the frame carrying the endless chain relative to the horizontal. In accordance with this invention, the angular position of the digging frame, hence the depth of the trench is controlled by the angular relationship of a trailing shoe carried by the digging frame relative to the digging frame. The trailing shoe has an elongated horizontal bottom surface that normally rides along the bottom of the formed trench. An upstanding mast is secured to the shoe at a point forwardly of the bottom surface and means on the top of the mast are utilized to indicate and control the depth of the trench.

Claims

1. In a trencher of the type having an endless chain carrying a plurality of digging scoops peripherally around an elongated digging frame, said digging frame having the forward end thereof pivotally mounted on a vehicle for movements in a vertical plane parallel to the path of travel of the vehicle, and means on the vehicle for driving said chain, the improvement comprising:

1. a sub-frame overlying said digging frame and having its front end rigidly secured to said digging frame;

2. a trench bottom shoe having an elongated bottom surface adapted to ride on the bottom of the newly dug trench, and means for pivotally mounting said shoe to the trailing end of said sub-frame for pivotal movements about a single horizontal axis provided on said digging frame, whereby said bottom surface is immediately tilted by variations in vertical position of said axis;

3. a cylinder for positioning said digging frame relative to said vehicle, thereby controlling the effective depth of the trench being dug;

4. means for establishing a reference plane at a known elevation;

5. an upstanding mast having its bottom end rigidly secured to said shoe at a point horizontally ahead of said bottom surface of said shoe, said mast being perpendicular to said bottom surface, whereby any upward or downward pivotal movement of said shoe relative to the digging frame produces a reverse tilting movement of the top of said mast relative to said reference plane, and

3. The apparatus defined in claim 1 wherein said means for establishing a reference plane comprises a horizontal bar mounted on an adjustable height vertical support rod, and said means on the top of said mast comprises a horizontal sighting bar.

4. The apparatus defined in claim 1 wherein said means for establishing a reference plane comprises an adjustable height, rotary laser beam and said means on the top of said mast comprises a vertical stack of laser beam sensors.

2. means on the top of said mast for determining the height of said mast relative to said reference plane, andmeans for supplying fluid to said cylinder to maintain the top of said mast in a fixed vertical position with respect to said reference plane.

5. In a trencher of the type having an endless chain carrying a plurality of digging scoops peripherally around an elongated digging frame, said digging frame having the forward end thereof pivotally mounted on a vehicle for movements in a vertical plane parallel to the path of travel of the vehicle, the trailing end of said frame journaling a chain sprocket, and means on the vehicle for driving said chain, the improvement comprising:

1. a sub-frame overlying said digging frame and having its front end rigidly secured to said digging frame and its trailing end disposed in overlying relationship to the trailing end of said digging frame;

2. a trench bottom shoe having an elongated bottom surface adapted to ride on the bottom of the newly dug trench, and means for pivotally mounting said shoe to the trailing end of said subframe for pivotal movements solely about said sprocket axis, whereby said bottom surface is immediately tilted by variations in vertical position of said sprocket axis;

3. a cylinder for pivoting said digging frame relative to said vehicle, thereby determining the depth of the trench being dug;

4. an upstanding mast having its bottom end rigidly secured to said shoe at a point horizontally ahead of the bottom surface of said shoe, said mast being perpendicular to said elongated bottom surface, whereby any upward or downward pivotal movement of said shoe produced by variations in the height of said sprocket axis produces a reverse downward and upward tilting movement of the top of said mast with respect to the horizontal;

5. a horizontal sighting bar carried by the top of said mast, and

6. manual means for adjusting the height of said sighting bar whereby said operator may initially align said sighting bar with a fixed reference bar disposed along the path of travel of the trencher and thereafter effect manual adjustment of said cylinder to maintain the depth of the trench constant by maintaining said sighting bar in continuous visual alignment with said reference bar.

6. In a trencher of the type having an endless chain carrying a plurality of digging scoops peripherally around an elongated digging frame, said digging frame having the forward end thereof pivotally mounted on a vehicle for movements in a vertical plane parallel to the path of travel of the vehicle, the trailing end journaling a chain sprocket, and means on the vehicle for driving said chain, the improvement comprising:

1. means for periodically sweeping a laser beam over the working area where the trench is to be dug, said beam defining a reference plane of known height relative to the desired depth of the trench;

2. a sub-frame overlying said digging frame and having its front end rigidly secured to said digging frame;

3. a trench bottom shoe having an elongated bottom surface adapted to ride on the bottom of the newly dug trench, and means for pivotally mounting said shoe to the trailing end of said sub-frame for pivotal movement solely about said sprocket axis, whereby said bottom surface is immediately tilted by variations in vertical position of said sprocket axis;

4. a cylinder for positioning said digging frame relative to the vehicle, thereby determining the depth of the trench being dug;

5. an upstanding mast having its bottom end rigidly secured to said shoe at a point horizontally ahead of the bottom surface of said shoe, said mast being perpendicular to said elongated bottom surface, whereby any upward pivotal movement of said shoe relative to said sprocket axis produces a downward tilting movement of the top of said mast relative to said reference plane, and any downward pivotal movement of said shoe relative to said sprocket axis produces an upward tilting movement of the top of said mast relative to said reference plane;

6. laser beam sensors carried by the top portion of said mast; and

7. control circuits responsive to said sensors for operating said cylinder to vary the angular position of said digging frame to maintain the trench depth at said desired level below said laser beam reference plane.

7. In a trencher of the type having an endless chain carrying a plurality of digging scoops peripherally around an elongated digging frame, said digging frame having the forward end thereof pivotally mounted on a vehicle for movements in a vertical plane parallel to the path of travel of the vehicle, and the trailing end journaling a chain sprocket, and means on the vehicle for driving said chain, the improvement comprising:

8. means for periodically sweeping a laser beam over the working area where the trench is to be dug, said beam defining a reference plane of known height relative to the desired depth of the trench;

2. a sub-frame overlying said digging frame and having its front end rigidly secured to said digging frame;

the trailing end of said sub-frame being arcuately curved in a radius concentric with the axis of said sprocket;

3. a trench bottom shoe defining an arcuate passage for slidably receiving said trailing end of said sub-frame, said shoe having an elongated bottom surface adapted to ride on the bottom of the newly dug trench, whereby changes in vertical position of said sprocket axis produce an immediate tilting of said shoe;

4. a cylinder for positioning said digging frame relative to said vehicle, thereby determining the depth of the trench being dug;

5. an upstanding mast having its bottom end rigidly secured to said shoe at a point horizontally ahead of and above said bottom surface of said shoe, said mast being perpendicular to said elongated bottom surface, whereby any upward or downward pivotal movement of said shoe relative to said sprocket axis produces a reverse tilting movement of the top of said mast relative to said reference plane;

6. laser beam sensors carried by the top portion of said mast; and

7. control circuits responsive to said sensors for operating said cylinders to vary the angular position of said digging frame to maintain the trench depth at said desired level below said laser beam reference plane.