The present invention concerns a means as defined in the preamble to claim 1.

Under some circumstances a moving vehicle must be stopped or its motion must be decelerated by external means. This kind of a situation can come in question for example, when one must stop a vehicle, whose driver, for example an escaping traffic violator, will not voluntarily stop.

It is known in prior art of stopping land vehicles by force to use a means, which has been described in the applicant's Finnish patent application FI 892560. This means comprises an elongated net which has been arranged to grab hold of the moving vehicle, which net comprises a head rope and a foot rope. Also the means comprise a first mast and a second mast, which masts have been set up at both ends of the net and have been arranged to keep the net tensioned between the masts. Additionally the means comprise brake members, which have been connected between the net and the substantially rigid support points to both net ends into the head and foot rope, and which brake members have been arranged to absorb the kinetic energy of the moving vehicle. In some countries it is required, that the means to stop a vehicle can be utilized unexpectedly, ie. to stop a vehicle without advance warning by lifting the net up from the ground only then, when the vehicle to be stopped is very near the net. A means of this nature is described in the international patent application publication WO 89/10302, where a solution is presented, where a net is in its initial position spread laying on the surface of the road, but is pulled up with ropes to the support of vertical masts when the vehicle to be stopped is near. Thus, at first the masts are upright and the net lays freely on the road without any

support.

The problem in this prior known means to stop a vehicle is, that while the net lays on ground ready for the surprise attack it can not be driven over with vehicles from either direction without the net being drifted from its initial set up due to the air turbulence of the passing vehicles. As a result of this the net can be bundled during lift up for example in such a way, that the foot rope hangs from the head rope, in which case the function of the means is not as planned. The vehicle to be stopped may be imcomplete grabbed into the net or drive under the net and thus slide through.

Furthermore a problem with the means known from the publication WO 89/10302 is, that it is utmost complicated to use.

The object of the invention is to eliminate the drawbacks mentioned above.

Especially the object of the invention is to present a means, where the net stays all the time tensioned both in its upright and its downlaying positions, thus the net in its downlaying position can be driven over from either direction without the net losing its ability of function when lifted up. The object of the invention is additionally to present a means, which makes possible a controlled and safe stopping of a moving vehicle.

In order to accomplish this, the means of the invention for slowing down and/or stopping the motion of a land vehicle is characterized by that which has been stated in claim 1.

According to the invention, the masts have been arranged to pivot between the substantially horizontal downlaying position where the net lays on the ground and the substantially vertical upraised position; that into the system belong yeild members, which connect the head rope and/or the foot rope to the masts substantially

tense in order to keep the net tight in its upraised and downlaying positions, and that the yeild members have been adjusted to yeild at a predetermined tensile force and release their hold after a predetermined yeild distance, and to keep the net tight when other vehicles drive over the downlaying net and when the vehicle to be stopped drives into the upraised net during the yeild distance.

In an embodiment of the means, the yeild distance of the yeild member is l - 10 m, suitably 1,5 to 4 m and advantageously 2 m.

In an embodiment of the means, the yeild member is a prior known fabric brake, which gives up after yeild. By giving up it is meant here, that the yeild member releases its hold on the net.

In an embodiment of the means, the fabric brake comprises two ribbons, which have been sewn together for the yeild distance. The sewing together of the ribbons is ibn most cases enough to provide for the adequate yeilding force.

In an embodiment of the means, into the yeild member on both sides of the yield section has been arranged pull ropes, comprising a first pull rope and a second pull rope; the first pull rope comprising a quick attachment member to attach it fast to the net; and the mast comprising a quick tensioning member to fast attachment of the second pull rope to the mast. The assembly of the means ready for the stopping is very easy and fast with the aid of the quick attachment and tensioning members. These components can be of known type used frequently in sailboats.

In an embodiment of the means, the yeild force of the yeild member is adjusted to higher level than the force, which occur while manually tensioning the net. When the net is manually tensioned, it is advantageous, if there is yet no yeild during tensioning.

In an embodiment of the means, the yeild force of

the yeild member is 400 - 600 ϊ~, advantageously 500 N.

In an embodiment of the means, the brake members comprise first brake members and second brake members and the first brake member and the second brake member have been arranged to both ends of the net, when the first brake member of both ends of the net is connected to the nearest end of the net and the second brake member is connected to the opposite end of the net, and the first brake member is of the type which releases its hold after yeilding and the second brake member is of the type which locks after yeilding; and the first brake member comprises the mentioned yeilding member.

It is an advantage of the invention, that when the net is in its downlaying position the vehicles can drive over it in either direction without the net getting entangled and this enables a trouble-free surprise stopping.

Furthermore it is an advabtage of the invention, that the net remains taut all the time from the beginning to the stop of the vehicle.

In addition, the invention enables a controlled and safe stopping of a moving land vehicle.

In the following the invention is described in detail, referring to the attached drawing, wherein:- Fig.l present schematically in side view an embodiment of the means of the invention,- and

Fig.2 shows a detail of the means in Fig. l.

In Fig.l is depicted a means for stopping the motion of a land vehicle, comprising an elongated net 1 to grab hold a vehicle in motion, which net comprises a head rope 2 and a foot rope 3. The net 1 has been arranged to be lifted up across the drive path of the oncoming vehicle. Furthermore, the means comprise a first mast 4 ¹ and a second mast A ² , which masts have been set up at both ends of the net and have been arranged to keep the net tensioned between the masts. Additionally, the means comprise brake members 5 ¹ , 5 ² , which have been

connected between the net and the substantially rigid support points 6 ¹ , 6 ² to both net ends into the head and foot rope. The brake members 5 ¹ , 5 ² have been arranged to absorb the kinetic energy of the moving vehicle. The support points 6 ¹ , 6 ² have been here held stationary with anchor vehicles. The masts 4 ¹ , 4 ² have been arranged to pivot between the substantially horizontal downlaying position, where the net lays on the ground and the substantially vertical upraised position. In Fig. 2 is depicted the into the means belonging yeild members 7 ¹ , 7 ² , which connect the head rope 2 and the foot rope 3 to the top and bottom end of the mast 4 substantially tense in order to keep the net tight in its upraised and downlaying positions. In Fig. 2 is by purpose not depicted the brake members, which belong into the means and can be arranged in known ways. The yeild members 7 ¹ , 7 ² have been adjusted to yeild at a predetermined tensile force and finally release their hold after a predetermined yeild distance, and to keep the net tight when other vehicles drive over the downlaying net and when the vehicle to be stopped drives into the upraised net during the yeild distance. In an arresting situation the net is not loose for even one moment and there does not occur any unwanted impulsive jerks, which might help the vehicle to be stopped to come off the net.

The length of the yeild member 7 ¹ , 7 ² is 1 - 10 m, suitably 1,5 - 4 m and advantageously 2 m. The yeild member 7 ¹ , 7 ² is a device of the fabric brake type, which releases- its hold after the yeild, where two ribbons are sewn together to provide for a predetermined yeild distance and the device functions in such a way, that the ribbons are teared apart, which creates a constant resistance force. Into the yeild member 7 ¹ , 7 have been arranged on both sides of the yeilding section pull ropes, which comprise a first pull rope 10 and a second pull rope 11.

The first pull rope 10 comprises a quick attachment member 12 to attach into the net. The mast 4 comprises quick tensioning members 13 to attach the second pull ropes 11 to the mast. The pull rope 11 of the yeild member 7 ¹ goes around:an angle guiding member 14 at the top of the mast to the quick attachment member 13. In similar way at the bottom of the mast the pull rope 11 of the yeild member 7 goes around the angle guiding member 14 to the quick attachment member 13. The yeild force of the yeild members 7 ¹ , 7 ² is adjusted to higher level than the force, which occur while manually tensioning the net. The reason for this is, that the net is tensioned between the masts in a hurry and then it is difficult to estimate such a tensioning force, which does not yet cause yeilding of the yield member. Thus the yeild force of the yeild members 7 ¹ , 7 ² is adjuste to 400 - 600 N, advantageously 500 N.

The invention is not confined exclusively to concern the embodiment examples presented in the foregoing: numerous modifications .are feasible while keeping within scope of the inventive idea defined by the claims.