Patent GB-1513328-A (GB)
Title: Parallel motion system for a bucket or the like in loading machines power shovels or the like
IPC: E02F3/43
Filed: 1976-04-15
Abstract: 1513328 Controlling buckets on excavators S O HAMMARSTRAND 15 April 1976 [17 April 1975] 15759/76 Heading B8H A lift arm 2, such as is used in a mechanical excavator, Fig. 1 (not shown), is pivoted at 4 and may be raised and lowered by an actuator 5 controlled by a valve 31 through line 36, valve 47, line 38 and line 37, valve 45 and line 39. A bucket 9 is shown pivoted on the arm 2 at 8 and may be tilted relative to the arm 2 by an actuator 10, acting, through links, on a pivot 14 and controlled by a valve 32 through lines 40, 41. A pulley 17 is connected to the bucket 9 to rotate with it as indicated by doubleheaded arrow P2. A cable 19 is partly wound on the pulley 17 and runs over free pulleys 18, 16 to a transmission bar 58 which includes a toothed portion 60, a tension spring 59 connecting the transmission bar 58 to a part of the excavator chassis 3. Movement of the bucket 9 relative to the arm 2 thus results in movement of the transmission bar 58 as indicated by a doubleheaded arrow P4. A locking pin 55 of an arresting means 54 may be optionally brought into engagement with the toothed portion 60 of the transmission bar 58 under the actuation of impulses from a push-button 56. The arresting means 54 is connected by setting bar 48 to the valve 45 which is connected by a bar 46 to the valve 47. The valve 45 has an intermediate positioning means 53 comprising opposed compression springs 50, 51 acting on a washer 52 fixed to the setting bar 48. When the pin 55 is withdrawn from engagement with the toothed section 60 of the transmission bar 58, Fig. 3 (not shown), the valves 45, 47 make the connections shown and are unaffected by movement of the transmission bar 58. This arrangement allows valve 31 to control the position of the lift arm 2 and valve 32 to control the adjustment of the bucket 9 relative to the lift arm 2 the one independently of the other and isolated therefrom. Actuation of the push-button 56 to cause the locking pin 55 to engage the toothed section 60 of the transmission bar 58 and using the valve 31 to cause actuator 5 to raise the lift arm 2 causes the transmission bar 58 to drop and valve 45 to connect line 36 to line 43 and line 39 to line 42, line 37 remaining connected to line 38, Fig. 4 (not shown). Under these conditions fluid from the actuator 5 following a path along lines 39, 42, 40 enters the actuator 10 to cause the bucket 9 to maintain its orientation with respect to the ground as the lift arm 2 is raised. When, with the locking pin 55 engaged with the toothed section 60 of the transmission bar 58, the valve 31 is actuated, with the valves 45, 47 in the intermediate position shown, to lower the lift arm 2, transmission bar 58 is raised and the valve 45 again connects line 36 to line 43 and line 39 to line 42, while line 37 remains connected to line 38, Fig. 5 (not shown). As described above the bucket 9 is caused to maintain its orientation with respect to the ground but this time as the lift arm is lowered. If the lowering is very rapid the valve 47 is caused to disconnect line 38 from line 37 and to connect line 38 to line 44, Fig. 5 (not shown), fluid from the cylinder 5 following lines 38, 44 assisting pump 24 to provide enough fluid to the actuator 10 to provide parallel motion of the bucket 9. Fig. 8 shows an embodiment of the valves 45, 47 in a single unit including intermediate positioning means 71-76.