Council Directive of 28 June 1977 on the approximation of the laws of the Member States relating to the roll-over protection structures of wheeled agricultural or forestry tractors (77/536/EEC) (repealed)

ANNEX III U.K. TEST PROCEDURES

A — TEST METHOD I U.K.

1. IMPACT AND CRUSHING TESTS U.K.

1.1. Impact at the rear U.K.

1.1.1. The tractor shall be so placed in relation to the weight that the weight will strike the roll-over protection structure when the impact face of the weight and the supporting chains or wire ropes are at an angle of 20° to the vertical unless the roll-over protection structure at the point of contact has, during deflection, a greater angle to the vertical. In this case the impact face of the weight shall be adjusted by means of an additional support so that it is parallel to the roll-over protection structure at the point of impact at the moment of maximum deflection, the supporting chains or wire ropes remaining at an angle of 20° to the vertical. Steps must be taken to reduce the tendency of the weight to turn about the point of contact. The suspended height of the weight shall be so adjusted that the locus of its centre of gravity passes through the point of contact. U.K.

The point of impact shall be that part of the roll-over protection structure likely to hit the ground first in a rearward overturning accident, normally the upper edge. The position of the centre of gravity of the weight shall be one-sixth of the width of the top of the roll-over protection structure inwards from a vertical plane parallel to the median plane of the tractor touching the outside extremity of the top of the roll-over protection structure.

However, if a curve in the back of the roll-over protection structure starts at a greater distance than this inside this vertical plane, the impact shall be administered at the beginning of the curve, i.e. at the point where this curve is tangential to a line at right angles to the median plane of the tractor (see Annex IV, fig. 9).

If a protruding member would present an inadequate area for the weight, a steel plate of appropriate thickness and depth and about 300 mm in length shall be fastened to that member in such a manner that the strength of the roll-over protection structure is not affected.

1.1.2. Tractors with rigid bodies shall be lashed down. The points of attachment of the lashings shall be approximately 2 m behind the rear axle and 1·5 m in front of the front axle. They shall either be in the plane in which the centre of gravity of the pendulum will swing or more than one lashing shall give a resultant force in this plane, as in Annex IV, fig. 5. U.K.

The lashings shall be tightened so that the deflections in the front and rear tyres are as indicated in 3.1.5 of Annex II. When the lashings have been tightened, a wooden beam 150 mm square shall be clamped in front of the rear wheels and driven tight against them.

1.1.3. Articulated tractors shall have both axles lashed down. The axle of that section of the tractor on which the roll-over protection structure is mounted shall be treated as the rear axle in Annex IV, fig. 5. The point of articulation will then be supported by a beam 100 mm square and will be lashed down firmly by means of wire ropes attached to the ground rails. U.K.

1.1.4. The weight shall be pulled back so that the height of its centre of gravity above that at the point of impact is given by the formula: U.K.

where H is the height of fall in millimetres and W the mass of the tractor as defined in 1.3 of Annex II.

The weight shall then be released and allowed to crash against the roll-over protection structure.

1.2. Impact at the front U.K.

1.2.1. The tractor shall be so placed in relation to the weight that the weight will strike the roll-over protection structure when the impact face of the weight and the supporting chains or wire ropes are at an angle of 20° to the vertical unless the roll-over protection structure at the point of contact has, during deflection, a greater angle to the vertical. In this case the impact face of the weight shall be adjusted by means of an additional support so that it is parallel to the roll-over protection structure at the point of impact at the moment of maximum deflection, the supporting chains or wire ropes remaining at an angle of 20° to the vertical. Steps must be taken to reduce the tendency of the weight to turn about the point of contact. The suspended height of the weight shall be so adjusted that the locus of its centre of gravity passes through the point of contact. U.K.

The point of impact shall be that part of the roll-over protection structure likely to hit the ground first if the tractor overturned sideways whilst travelling forward, normally the top front corner. The position of the centre of gravity of the weight shall be not more than 80 mm from a vertical plane parallel to the median plane of the tractor touching the outside extremity of the top of the roll-over protection structure.

However, if a curve in the front of the roll-over protection structure starts at a greater distance than 80 mm inside this vertical plane, the impact shall be administered at the beginning of the curve, i.e. at the point where this curve is tangential to a line at right angles to the median plane of the tractor (see Annex IV, fig. 9).

1.2.2. Tractors with rigid bodies shall be lashed down as indicated in Annex IV, fig. 6. The points of attachment of the lashings shall be approximately 2 m behind the rear axle and 1·5 m in front of the front axle. U.K.

The lashings shall be tightened so that the deflections in the front and rear tyres are as indicated in 3.1.5 of Annex II. When the lashings have been tightened, a wooden beam approximately 150 mm square shall be clamped behind the rear wheels and driven tight against them.

1.2.3. Articulated tractors shall have both axles lashed down. The axle of that section of the tractor on which the roll-over protection structure is mounted shall be treated as the front axle in Annex IV, fig. 6. The point of articulation shall then be supported by a beam approximately 100 mm square and shall be lashed down firmly by means of wire ropes attached to the ground rails. U.K.

1.2.4. The weight shall be pulled back so that the height of its centre of gravity above that at the point of impact is given by the formula: U.K.

.

1.3. Impact at the side U.K.

1.3.1. The tractor shall be so placed in relation to the weight that the weight will strike the roll-over protection structure when the impact face of the weight and the supporting chains or wire ropes are vertical unless the protection structure at the point of contact is, during deflection, other than vertical. In this case the impact face of the weight shall be adjusted by means of an additional support so that it is parallel to the protection structure at the point of impact at the moment of maximum deflection, the supporting chains or wire ropes remaining vertical. The suspended height of the weight shall be so adjusted that the locus of its centre of gravity passes through the point of contact. U.K.

The point of impact shall be that part of the roll-over protection structure likely to hit the ground first in a sideways overturning accident, normally the upper edge. Unless it is certain that another part of this edge would hit the ground first, the point of impact shall be in the plane at right angles to the median plane of the tractor and passing through the middle of the seat at the mid-point of adjustment. Steps must be taken to reduce the tendency of the weight to turn about the point of contact.

1.3.2. For rigid tractors, any axle the position of which is rigid relative to the protection structure shall be lashed down on the side on which the impact is to be administered. In the case of a two-wheel drive tractor this will normally be the rear axle; this arrangement is shown in Annex IV, fig. 7. The two lashings shall pass over the axle from points directly below it, one passing to a point of attachment approximately 1·5 m in front of the axle and the other to a point approximately 1·5 m behind the axle. The lashings shall be tightened so that there is a deflection in the tyre adjacent to the lashing as indicated in 3.1.5 of Annex II. After lashing, a wooden beam shall be placed as a prop against the wheel opposite the weight and secured to the floor so that it is held tightly against the wheel rim during impact as shown in Annex IV, fig. 7. The length of the beam shall be chosen so that when in position against the wheel it is at an angle of 30 ± 3° to the horizontal. Its length shall be 20 to 25 times its thickness and its width two to three times its thickness. Both axles shall be prevented from moving sideways by means of a beam clamped to the floor against the outside of the wheel on the side opposite that on which the impact is to be administered. U.K.

1.3.3. An articulated tractor must be lashed down so that the section of the tractor bearing the protection structure is fixed rigidly to the ground as in the case of a non-articulated tractor. U.K.

Both axles of articulated tractors shall be lashed to the ground. The axle and wheels of that section of the tractor on which the protection structure is mounted shall be lashed and propped as in Annex IV, fig. 7. The point of articulation shall be supported by a beam at least 100 mm square and lashed down to the ground rails. A prop will be positioned against the point of articulation and secured to the floor so that it has the same effect as a prop against the rear wheel and provides support similar to that achieved for a rigid tractor.

1.3.4. The weight shall be pulled back so that the height of its centre of gravity above that at the point of impact is given by the formula: U.K.

.

1.4. Crushing at the rear U.K.

The tractor shall be positioned in the rig described in 2.6 of Annex II and shown in Annex IV, figs. 8 and 10, in such a way that the rear edge of the beam is over the rearmost top load-bearing part of the protection structure and the median longitudinal plane of the tractor is midway between the points of application of force to the beam.

The axle stands shall be placed under the axles in such a way that the tyres do not bear the crushing force. The force applied shall correspond to twice the mass of the tractor as defined in 1.3 of Annex II. It may be necessary to lash down the front of the tractor.

1.5. Crushing at the front U.K.

1.5.1. This shall be identical to the crushing test at the rear except that the front edge of the beam shall be over the frontmost top part of the roll-over protection structure. U.K.

1.5.2. Where the front part of the protection structure roof will not sustain the full crushing force, the force shall be applied until the roof is deflected to coincide with the plane joining the upper part of the roll-over protection structure with that part of the front of the tractor capable of supporting the tractor's mass when overturned. The force shall then be removed and the tractor re-positioned so that the beam is over that point of the protection structure which would then support the rear of the tractor when completely overturned, as shown in Annex IV, fig. 10, and the full force reapplied. U.K.

2. ZONE OF CLEARANCE U.K.

2.1. The ‘zone of clearance’ is defined by planes as follows, the tractor being on a horizontal surface: U.K.

• horizontal, 95 cm above the compressed seat;

• vertical, perpendicular to the median plane of the tractor and 10 cm behind the back of the seat;

• vertical, parallel to the median plane of the tractor and 25 cm to the left of the centre of the seat;

• vertical, parallel to the median plane of the tractor and 25 cm to the right of the centre of the seat;

• an inclined plane in which lies a horizontal line which is at right angles to the median plane of the tractor, 95 cm above the compressed seat and 45 cm (plus the normal fore and aft movement of the seat) in front of the back of the seat. This inclined plane passes in front of the steering wheel and at its nearest point is 4 cm from the rim of the steering wheel.

2.2. The back of the seat shall be determined ignoring any padding thereon. The seat shall be in its rearmost adjustment for normal seated operation of the tractor and in its highest position if this is independently variable. Where the suspension of the seat is adjustable it shall be at its mean setting and the load on it shall be 75 kg. U.K.

3. MEASUREMENTS TO BE MADE U.K.

3.1. Fractures and cracks U.K.

After each test all structural members, joints and attaching brackets on the tractor shall be visually examined for fractures or cracks, any small cracks in unimportant parts being ignored.

3.2. Zone of clearance U.K.

3.2.1. After each test the roll-over protection structure shall be examined to see whether any part of the protection structure has entered a zone of clearance round the driving seat as defined in 2. U.K.

3.2.2. In addition, the protection structure shall be examined to determine whether any part of the zone of clearance is outside the protection of the protection structure. For this purpose it shall be considered to be outside the protection of the structure if any part of it would have come in contact with flat ground if the tractor had overturned towards the direction from which the impact came. For this purpose the tyre and track setting shall be assumed to be the smallest indicated by the manufacturer. U.K.

3.3. Maximum momentary deflection U.K.

During the side impact test the difference between the maximum momentary deflection and the residual deflection at a height of 950 mm above the loaded seat shall be recorded. One end of the rod described in 2.7.1 of Annex II shall be attached to the upper part of the roll-over protection structure and the other end passed through a hole in the vertical standard. The position of the friction collar on the rod after the impact indicates the maximum momentary deflection.

3.4. Permanent deflection U.K.

After the final compression test the permanent deflection of the protection structure shall be recorded. For this purpose, before the start of the test, the positions of the main roll-over protection structure members in relation to the seat shall be recorded.

B — TEST METHOD II U.K.

1. IMPACT AND CRUSHING TESTS U.K.

1.1. Impact at the rear U.K.

1.1.1. The tractor shall be so placed in relation to the weight that the weight will strike the roll-over protection structure when the impact face of the weight and the supporting chains or wire ropes are at an angle of 20° to the vertical unless the roll-over protection structure at the point of contact has, during deflection, a greater angle to the vertical. In this case the impact face of the weight shall be adjusted by means of an additional support so that it is parallel to the roll-over protection structure at the point of impact at the moment of maximum deflection, the supporting chains or wire ropes remaining at an angle of 20° to the vertical. Steps must be taken to reduce the tendency of the weight to turn about the point of contact. The suspended height of the weight shall be so adjusted that the locus of its centre of gravity passes through the point of contact. U.K.

The point of impact shall be that part of the roll-over protection structure likely to hit the ground first in a rearward overturning accident, normally the upper edge. The position of the centre of gravity of the weight shall be one-sixth of the width of the top of the roll-over protection structure inwards from a vertical plane parallel to the median plane of the tractor touching the outside extremity of the top of the roll-over protection structure.

However, if a curve in the back of the roll-over protection structure starts at a greater distance than this inside this vertical plane, the impact shall be administered at the beginning of the curve, i.e. at the point where this curve is tangential to a line at right angles to the median plane of the tractor (see Annex IV, fig. 9).

If a protruding member would present an inadequate area for the weight, a steel plate of appropriate thickness and depth and about 300 mm in length shall be fastened to that member in such a manner that the strength of the roll-over protection structure is not affected.

1.1.2. Tractors with rigid bodies shall be lashed down. The points of attachment of the lashings shall be approximately 2 m behind the rear axle and 1·5 m in front of the front axle. They shall either be in the plane in which the centre of gravity of the pendulum will swing or more than one lashing shall give a resultant force in this plane, as in Annex IV, fig. 5. U.K.

The lashing shall be tightened so that the deflections in the front and rear tyres are as indicated in 3.1.5 of Annex II. After the lashings have been tightened a wooden beam 150 mm square shall be clamped in front of the rear wheels and driven tight against them.

1.1.3. Articulated tractors shall have both axles lashed down. The axle for that section of the tractor on which the roll-over protection structure is mounted shall be treated as the rear axle in Annex IV, fig. 5. The point of articulation will then be supported by a beam 100 mm square minimum and will be lashed down firmly by means of wire ropes attached to the ground rails. U.K.

1.1.4. The weight shall be pulled back so that the height of its centre of gravity above that at the point of impact is given by the formula: U.K.

or

where:

H

=

the height of fall in millimetres,

W

=

the mass of the tractor as defined in 1.3 of Annex II,

L

=

the maximum tractor wheelbase in millimetres,

I

=

the moment of inertia of the rear axle, with wheels removed, in kilograms per square metre (kg/m²).

The weight shall then be released and allowed to crash against the roll-over protection structure.

1.1.5. There shall be no rear impact in the case of a tractor at least 50 % of the mass of which, as defined in 1.3 of Annex II, bears on the front axle. U.K.

1.2. Impact at the front U.K.

1.2.1. The tractor shall be so placed in relation to the weight that the weight will strike the roll-over protection structure when the impact face of the weight and the supporting chains or wire ropes are at an angle of 20° to the vertical unless the roll-over protection structure at the point of contact has, during deflection, a greater angle to the vertical. In this case the impact face of the weight shall be adjusted by means of an additional support so that it is parallel to the roll-over protection structure at the point of impact at the moment of maximum deflection, the supporting chains or wire ropes remaining at an angle of 20° to the vertical. Steps must be taken to reduce the tendency of the weight to turn about the point of contact. The suspended height of the weight shall be so adjusted that the locus of its centre of gravity passes through the point of contact. U.K.

The point of impact shall be that part of the protection structure likely to hit the ground first if the tractor overturned sideways whilst travelling forward, normally the top front corner. The position of the centre of gravity of the weight shall be not more than 80 mm from a vertical plane parallel to the median plane of the tractor touching the outside extremity of the top of the roll-over protection structure.

However, if a curve in the front of the roll-over protection structure starts at a greater distance than 80 mm inside this vertical plane, the impact shall be administered at the beginning of the curve, i.e. at the point where this curve is tangential to a line at right angles to the median plane of the tractor (see Annex IV, fig. 9).

1.2.2. Tractors with rigid bodies shall be lashed down as illustrated in Annex IV, fig. 6. The points of attachment of the lashings shall be approximately 2 m behind the rear axle and 1·5 m in front of the front axle. U.K.

The lashings shall be tightened so that the deflections in the front and rear tyres are as indicated in 3.1.5 of Annex II. When the lashings have been tightened, a wooden beam 150 mm square shall be clamped behind the rear wheels and driven tight against them.

1.2.3. Articulated tractors shall have both axles lashed down. The axle of that section of the tractor on which the roll-over protection structure is mounted shall be treated as the front axle in Annex IV, fig. 6. The point of articulation shall then be supported by a beam 100 mm square minimum and shall be lashed down firmly by means of wire ropes attached to the ground rails. U.K.

1.2.4. The weight shall be pulled back so that the height of its centre of gravity above that at the point of impact is given by the formula: U.K.

.

1.3. Impact at the side U.K.

1.3.1. The tractor shall be so placed in relation to the weight that the weight will strike the roll-over protection structure when the impact face of the weight and the supporting chains or wire ropes are vertical unless the protection structure at the point of contact is, during deflection, other than vertical. In this case the impact face of the weight shall be adjusted by means of an additional support so that it is parallel to the protection structure at the point of impact at the moment of maximum deflection, the supporting chains or wire ropes remaining vertical. The suspended height of the weight shall be so adjusted that the locus of its centre of gravity passes through the point of contact. U.K.

The point of impact shall be that part of the protection structure likely to hit the ground first in a sideways overturning accident, normally the upper edge. Unless it is certain that another part of this edge would hit the ground first, the point of impact shall be in the plane at right angles to the median plane of the tractor and passing through the middle of the seat at the mid-point of adjustment. Steps must be taken to reduce the tendency of the weight to turn about the point of contact.[F1 In the case of a tractor with a reversible driving position (i.e. with a reversible seat and steering wheel), the point of impact shall be determined in relation to the intersection of the median plane of the tractor and of a plane perpendicular to it, by a straight line passing through a point that is equidistant from the two seat reference points.]

Textual Amendments

F1 Inserted by Commission directive 1999/55/EC of 1 June 1999 adapting to technical progress Council Directive 77/536/EEC relating to the roll-over protection structures of wheeled agricultural or forestry tractors (Text with EEA relevance).

1.3.2. For rigid tractors, any axle the position of which is rigid relative to the protection structure shall be lashed down on the side on which the impact is to be administered. In the case of a two-wheel drive tractor this will normally be the rear axle; this arrangement is shown in Annex IV, fig. 7. The two lashings shall pass over the axle from points directly below it, one passing to a point of attachment approximately 1·5 m in front of the axle and the other to a point approximately 1·5 m behind the axle. The lashings shall be tightened so that there is a deflection in the tyre adjacent to the lashing as indicated in 3.1.5 of Annex II. After lashing, a wooden beam shall be placed as a prop against the wheel opposite the weight and secured to the floor so that it is held tightly against the wheel rim during impact as shown in Annex IV, fig. 7. The length of the beam shall be chosen so that when in position against the wheel it is at an angle of 30 ± 3° to the horizontal. Its length shall be 20 to 25 times its thickness and its width two to three times its thickness. Both axles shall be prevented from moving sideways by means of a beam clamped to the floor against the outside of the wheel on the side opposite that on which the impact is to be administered. U.K.

1.3.3. An articulated tractor must be lashed down so that the section of the tractor bearing the protection structure is fixed rigidly to the ground as in the case of a non-articulated tractor. U.K.

Both axles of articulated tractors shall be lashed to the ground. The axle and wheels of that section of the tractor on which the protection structure is mounted shall be lashed and propped as in Annex IV, fig. 7. The point of articulation shall be supported by a beam at least 100 mm square and lashed down to the ground rails. A prop will be positioned against the point of articulation and secured to the floor so that it has the same effect as a prop against the rear wheel and provides support similar to that achieved for a rigid tractor.

1.3.4. The weight shall be pulled back so that the height of its centre of gravity above that at the point of impact is given by the formula: U.K.

.

1.4. Crushing at the rear U.K.

The tractor shall be positioned in the rig described in 2.6 of Annex II and shown in Annex IV, figs. 8 and 10 in such a way that the rear edge of the beam is over the rearmost top load-bearing part of the roll-over protection structure and the median longitudinal plane of the tractor is midway between the points of application of force to the beam.

The axle stands shall be placed under the axles in such a way that the tyres do not bear the crushing force. The force applied shall correspond to twice the mass of the tractor as defined in 1.3 of Annex II. It may be necessary to lash down the front of the tractor.

1.5. Crushing at the front U.K.

1.5.1. This test shall be identical to the crushing test at the rear except that the front edge of the beam shall be over the frontmost top part of the roll-over protection structure. U.K.

1.5.2. Where the front part of the roll-over protection structure roof cannot sustain the full crushing force, the force shall be applied until the roof is deflected to coincide with the plane joining the upper part of the roll-over protection structure with that part of the front of the tractor capable of supporting the tractor's mass when overturned. The force shall then be removed and the tractor re-positioned so that the beam is over that point of the roll-over protection structure which would then support the rear of the tractor when completely over-turned as shown in Annex IV, fig. 10, and the full force reapplied. U.K.

2. ZONE OF CLEARANCE U.K.

2.1. The zone of clearance is illustrated in Annex IV, fig. 3, and is defined in relation to a vertical reference plane generally longitudinal to the tractor and passing through a seat reference point, described in 2.3, and the centre of the steering wheel. The reference plane shall be assumed to move horizontally with the seat and steering wheel during impacts but to remain perpendicular to the floor of the tractor or of the roll-over protection structure if this is resiliently mounted. U.K.

Where the steering wheel is adjustable, its position should be that for normal seated driving.

2.2. The boundaries of the zone shall be taken as: U.K.

2.2.1. vertical planes 250 mm on either side of the reference plane extending upwards from the seat reference point for 300 mm; U.K.

2.2.2. parallel planes extending from the upper edge of planes 2.2.1 to a maximum height of 900 mm above the seat reference point and inclined in such a way that the upper edge of the plane on the side from which the side impact is struck is at least 100 mm from the reference plane; U.K.

2.2.3. a horizontal plane 900 mm above the seat reference point; U.K.

2.2.4. an inclined plane perpendicular to the reference plane and including a point 900 mm directly above the seat reference point and the rearmost point of the seat structure including its suspension; U.K.

2.2.5. a vertical plane perpendicular to the reference plane extending downwards from the rear-most point of the seat; U.K.

2.2.6. a curvilinear surface, perpendicular to the reference plane, with a radius of 120 mm tangential to planes 2.2.3 and 2.2.4; U.K.

2.2.7. a curvilinear suface, perpendicular to the reference plane, having a radius of 900 mm and extending forward for 400 mm from and tangential to plane 2.2.3 at a point 150 mm forward of the seat reference point; U.K.

2.2.8. an inclined plane perpendicular to the reference plane, joining surface 2.2.7 at its forward edge and passing 40 mm from the steering wheel. In the case of a high steering wheel position this plane is replaced by a tangent plane to surface 2.2.7; U.K.

2.2.9. a vertical plane, perpendicular to the reference plane, 40 mm forward of the steering wheel; U.K.

2.2.10. a horizontal plane through the seat reference point[F2 ;] U.K.

Textual Amendments

F2 Substituted by Commission directive 1999/55/EC of 1 June 1999 adapting to technical progress Council Directive 77/536/EEC relating to the roll-over protection structures of wheeled agricultural or forestry tractors (Text with EEA relevance).

[F1 2.2.11. in the case of a tractor with a reversible driving position (i.e. with a reversible seat and steering wheel), the clearance shall be a combination of the two clearances determined by the two positions of the steering wheel and seat; U.K.

2.2.12. in the case of a tractor which can be fitted with optional seats, the tests shall be based on the combined clearance of the seat reference points for all available seat-fitting options. The roll-over protection structure must not enter the combined clearance around the various seat reference points; U.K.

2.2.13. where a new option for the seat is proposed after the test has taken place, a calculation is made to determine whether the clearance around the new seat reference point is located entirely within the combined clearance established previously. If this is not the case, a new test is required.] U.K.

2.3. Seat location and seat reference point U.K.

2.3.1. For the purpose of defining the zone of clearance in 2.1, the seat shall be at the rearmost point of any horizontal adjustment range. It shall be set at the mid-point of the vertical adjustment range where this is independent of adjustment of its horizontal position. U.K.

The reference point shall be established using the apparatus illustrated in Annex IV, figs. 1 and 2, to simulate loading by a human occupant. The apparatus shall consist of a seat pan board and backrest boards. The lower backrest board shall be jointed in the region of the ischium humps (A) and loin (B), the joint (B) being adjustable in height.

2.3.2. The reference point is defined as the point in the median longitudinal plane of the seat where the tangential plane of the lower backrest and a horizontal plane intersect. This horizontal plane cuts the lower surface of the seat pan board 150 mm in front of the abovementioned tangent. U.K.

2.3.3. Where a seat suspension is provided with adjustment for the weight of the driver, this shall be set so that the seat is at the mid-point of its dynamic range. U.K.

The apparatus shall be positioned on the seat. It shall then be loaded with a force of 550 N at a point 50 mm in front of joint (A), and the two parts of the backrest board shall be lightly pressed tangentially against the backrest.

2.3.4. If it is not possible to determine definite tangents to each area of the backrest (above and below the lumbar region) the following should be done: U.K.

2.3.4.1. where no definite tangent to the lower area is possible: the lower part of the backrest board is pressed against the backrest vertically; U.K.

2.3.4.2. where no definite tangent to the upper area is possible: the joint (B) is fixed at a height of 230 mm above the seat reference point, if the lower part of the backrest board is vertical. Then the two parts of the backrest board are lightly pressed against the backrest tangentially. U.K.

3. MEASUREMENTS TO BE MADE U.K.

3.1. Fractures and cracks U.K.

After each test all structural members, joints and attaching brackets on the tractor shall be visually examined for fractures or cracks, any small cracks in unimportant parts being ignored.

3.2. Zone of clearance U.K.

3.2.1. During each test the roll-over protection structure shall be examined to see whether any part of the roll-over protection structure has entered a zone of clearance round the driving seat as defined in 2.1 and 2.2. U.K.

3.2.2. In addition, the roll-over protection structure shall be examined to determine whether any part of the zone of clearance is outside the protection of the roll-over protection structure. For this purpose it shall be considered to be outside the protection of the roll-over protection structure if any part of it would have come in contact with flat ground if the tractor had overturned towards the direction from which the impact came. For this purpose the tyre and track setting shall be assumed to be the smallest specified by the manufacturer. U.K.

3.3. Maximum momentary deflection U.K.

During the side impact test the difference between the maximum momentary deflection and the residual deflection at a height of 900 mm above and 150 mm forward of the seat reference point shall be recorded. One end of the rod described in 2.7.1 of Annex II shall be attached to the upper part of the roll-over protection structure and the other end passed through a hole in the vertical standard. The position of the friction collar on the rod after the blow indicates the maximum momentary deflection.

3.4. Permanent deflection U.K.

After the final compression test the permanent deflection of the protection structure shall be recorded. For this purpose, before the start of the test, the position of the main roll-over protection structure members in relation to the seat reference point shall be recorded.