GB2038602A

GB2038602A - Improvements in ploughs

Info

Publication number: GB2038602A
Application number: GB7942793A
Authority: GB
Original assignee: Rabewerk Heinrich Clausing
Current assignee: Rabewerk Heinrich Clausing
Priority date: 1978-12-16
Filing date: 1979-12-12
Publication date: 1980-07-30
Also published as: ATA720979A; FR2443793A1; AT364183B; FR2443793B1; GB2038602B; CH643981A5

Abstract

A plough beam (1), whose forward end is pivoted to a plough frame so that the plough beam can swing upwardly when the ploughshare thereon encounters an obstruction, is provided with a bellcrank lever (20) at its rear end shown in Fig. 3. A spring is disposed in a tubular portion (2) of the beam (1) and acts on a carriage (34) to place a draw rod (16) under tension, the forward end of the latter being attached to the frame. Due to the location of the pivots (25 and 32) relative to the fulcrum (21) of the lever (20), the tension in the draw rod (16) is reduced as the plough beam swings up, despite the increasing compression of the spring. <IMAGE>

Description

SPECIFICATION Improvements in ploughs The invention relates to an obstruction protective means for reversible ploughs in which a right-hand turning and a left-turning plough-share are each secured to a T-shaped tubular plough beam which is swingable about double pivots and which accommo dates a spring which holds the plough beam in its working position and returns it to this position after it has been swung upwardly, ag. when the plough arc strikes an obstruction, such as a large stone.

In the automatically operating obstruction protective means described above, the turning movement at which the ploughshare commences to lift when it strikes an obstruction is determined by the dead weight of the two ploughshares mounted on a plough beam, and the spring force multiplied by their leverages relative to the centre of gravity of the plough beam. An increase in this moment during the swinging up operation is undesirable, since it can promote damange to the ploughshare. Thus, it is desirable to prevent the turning moment exerted by the spring from increasing despite the increasing force of the spring.

In accordance with the invention a reversible plough comprises at least one pair of ploughshares, each pair consisting of a right-hand turning and a left-hand turning ploughshare, the or each pair of ploughshares being secured to a T-shaped, tubular plough beam which is vertically swingable about double pivots and which accommodates a spring which holds the plough beam in its working position and returns it thereto after it has been swung up, and a draw rod which is articulated at one end to the plough frame and at its other end to a first pivot joint on one arm of a multi-arm lever pivotally mounted in the plough beam or at the rear end of the plough beam, the spring being operative at a second pivot joint on another arm of the multi-arm lever.

The bearings of the three pivots 6f the multi-arm lever can be disposed relative to one another and to the plough beam such that, upon swinging up the plough beam relative to the frame of the plough away from the working position, the associated spring is additionally compressed to a decreasing extent as the swinging up operation progresses. A bell-crank lever system of this kind renders it possible to limit the increase in the moment, during swinging up of the plough beam.

The invention will be further described hereinafter, by way of example, with reference to the drawings, in which: Fig. lisa side elevation of a plough beam having an obstruction protective means and shows a portion of the plough frame, Fig. 2 is a plan view of a detail of Fig. 1 at the forward end of the plough beam, Figs. 3 and 4 are partially sectioned plan and side views respectively of the lever system at the rear end of the plough beam, the plough being in its working position, and Fig. 5 shows the lever system of Fig. 3 in its swung-up position.

Fig. 1 shows a T-shaped plough beam 1 composed of a rectangular section tube portion 2 and a conical housing 3. Two trapezoidal plates 4 and 5 are welded to the tube 2 of the plough beam and serve to secure struts 6 of the ploughshares 7, only the left-hand turning ploughshare being illustrated. A housing 9 forming a shoulder is welded to the plough frame 8.

The top and bottom edges of the rearwall 10 of the housing 9 each carry two bearings lugs 11 through which are inserted axles 12 and 13 respectively. The plough beam housing 3 has bearings 14 adapted to the axles and is mounted on the latter. Thus, the plough beam 1 can swing upwardly about the axle 12 or can swing about the axle 13 when the plough frame 8 with the ploughshares thereon is turned over.

Furthermore, two bearing lugs 15 are secured to the rear wall 10 and serve to mount a rod 16 which acts as a movableabutmentfora-spring 17 which is fitted in the plough beam 2 and whose fixed abut mentwithin the plough beam is designated-18 (Fig.

2).

A cap or hood 19 is welded to the rear end of the tube portion 2 or the plough beam (Fig. 2). A multiarm lever 20 is pivotally mounted on a pin 21 within the hood 19. The lever 20 is a bellcrank lever and comprises two triangular plates which are spaced apart one above the other and which are intercon nected by means of a plate 22. The plates forming the lever 20 are thus located at each side of the rear end of the rod 16 whose head 23 forms a bearing 24 for a pin 25 which passes through two slotted holes 26 in the two plates forming the lever 20. The pin 25 is rigidly mounted in the limbs 27 of a bracket 28 which abuts by means of an adjustable screw 29 against a plate 30 which is connected to-the plates 20. The pin 25 thus forms a pivot joint for the draw rod 16.The screw 29 enables the rod 16 to be fixed in a play-free manner on the lever 20 when the position of the latter lever is changed. Such change can be effected by means of a screw 31 which acts upon the plate 22.

Furthermore, each plate 20 carries a stud 32. A bar 33 is pivotally mounted on each stud 32 and connects the lever 20 to a sliding carriage 34 in the tube portion 2 of the plough beam. The sliding carriage comprises a plate 35 which forms an abutment for the spring 17, and two lugs 36 having stubs 37. The bars 33 are pivotally mounted on the studs 37, and a circular disc 38 to serve as a guide wheel for guiding the sliding carriage 34 in the tube portion 2 of the plough beam is rotatably mounted on each of the studs 37. The studs 32 thus form a pivot joint for the spring 17. The sliding carriage itself prevents buckling of the spring 17 and, if necessary, can alternatively be provided with four discs 38 to serve as guide wheels.

Fig. 3 shows the lever 20 in the working position of the associated plough-share. The angle a between the rod 16 and the associated lever arm of the lever 20 and the angle,3 between the bar 33 and the associated lever arm are adjusted by means of the screw 31 such that the angle at in the undeflected state shown in Fig. 3 and the angle p2 in the maximum deflected state shown in Fig. 5 are each approximately 20 .

When the ploughshare 7 strikes an obstruction, such as a stone, it is swung upwardly about the pivot axle 12 so that the rod 16 turns the multi-arm lever 20 from the normal position of Fig. 3 in a clockwise direction towards the position shown in Fig. 5 and against the force of the spring 17 transmitted by the bars 33. From a comparison of Figs. 3 and 5, it can be seen that during this swinging-up, the leverage of the rod 16 about the lever pivot pin 21 increases whilst the leverage of the spring about this pivot pin decreases. In factthis change in lever ration is so great that the tension in the draw rod 16, and thus the moment resisting swing-up of the plough beam 1 decreases with the swing-up of the plough beam 1 decreases with the swinging-up of the plough beam 1, despite the increasing compression of the spring 17. This enables the ploughshare to clear the obstruction with reduced risk of damage to the plougharc.

Claims

1. A reversible plough comprising at least one pair-of ploughshares, each pair consisting of a right-hand turning and a left-hand turning ploughshare, the or each pair of ploughshares being secured to a T-shaped tubular plough beam which is vertically swingable about double pivots and which accommodates a spring which holds the plough beam in its working position and it returns it thereto after it has been swung up, and a draw rod which is articulated at one end to the plough frame and at its other end to a first pivot joint on one arm of a multi arm lever pivotally mounted in the plough beam or at the rear end of the plough beam, the spring being operative at a second pivot joint on another arm of the multi-arm lever.

2. A plough as claimed in claim 1, in which the resting position of the multi-arm lever is adjustable relative to the plough beam.

3. A plough as claimed in claim 1 or 2, in which the rear end of the spring arranged in the plough beam is guided by a sliding carriage.

4. A plough as claimed in claim 3, in which two or four circular and rototably mounted discs serve as wheels to guide the sliding carriage.

5. A plough as claimed in claim 3 or4, in which a connecting bar connects the carriage to the second pivot joint.

6. A plough as claimed in any preceding claim, in which the first pivot joint by which the draw rod is connected to an arm of the lever is adjustable.

7. A plough constructed substantially as herein described with reference to and as illustrated in the drawings.