The invention relates to a safety device preventing a person from falling when climbing on ladder. By the pressure of a spring mechanism, the safety device stops in a rail fixed to the ladder and prevents from falling when the person is suspended in the safety device.

In fire ladders and other access ladders a rail is used as safety device to which a carriage is fixed that moves in the rail and reacts upon dropping by stopping in the rail and thus preventing the safety device user from falling. Safety carriages are known, among others, from the Finnish publication 61133 and application 842035. In these examples, the safety carriage hits the rail or an obstacled formed in the profile. Among others T- profiles and square profiles and corresponding C-profiles are used, the profile of which is open at a point allowing the safety carriage to be guided off the rail.

The disadvantage of these carriages incl. said profiles is the carriage tendency to slip off the profile in stress situations. The C- or the square profiles yield by stress just so much that the opening tends to spread thus easening carriage to come out. In T- and I-profiles, as per publication DE-2626425, the profile side brackets easily bend outward due to great force transmitted over the carriage wheels. Then the carriage can protrude so much that the locking does not function anymore. In using above said carriage and rail types, the wall thickness must be sufficient.

With a carriage and a corresponding rail type according to the invention a decisive improvement of the safety devise propert¬ ies is achieved and, with respect to safety, the disadvantages of present devices are eliminated.

According to the invention, the profile is either a C- or a square profile, in each profile there is a gap for the carriage. At the gap edges the profile has rims bent to the profile in¬ side. In stress situations the C- and square profiles have the tendency to spread out thus enlargening the gap in the profile front edge. This is taken advantage of by fitting the carriage portion, which falls inside the profile, with two brackets which take, with the carriage locked, support from the profile gap flank and, simultaneously, also from the bent gap rims, thus preventing carriage, when stopped, to get off the profile and allowing the use of thinner profile material.

In the following the invention is more closely defined according to the enclosed drawing, where Fig. 1 is a carriage in a rail profile Fig. 2 is a rail profile

Fig. 3 is a stopped carriage, the rail a reduced cross-section of a situation as per figure 1 Fig. 4 is a carriage viewed diagonally

Fig. 1 shows a carriage 4 in rail profile 1. The carriage moves up and down in the rail while belt loop 5 is being pulled off the rail. The user suspends him/herself in the belt, one end of which is in belt loop 5. When carriage 4 is pulled from loop 5 on moving up or down in the ladder direction, the carriage does not stop in the collision brackets 2 arranged on the profile back wall.

Fig. 2 shows a rail profile 1, on the inside back wall of which curved brackets 2 are hammered by a tool at suitable intervals. In this profile type holes 13 are made between the brackets in the back wall for fastening the rail to the ladder. The rail profile design tapers towards the front edge, where the profile is open. At the edges of the produced gap the profile has rims 3 bent to the profile inside. The inner walls of these bent rims 3 are marked by ref.no 12.

Figure 3 shows a cross-section of a situation as per figure 1, where carriage 4 is stopped in rail 1. Carriage wheel 6, which can move in the carriage frame, is stretched toward belt loop 5 by spring 14 around pin 7 in carriage 4, whereupon carriage wheel 6 has hit the front edge of the rail and, accordinly, carriage 4 has then moved against the rail back wall by the impact of spring 14. Since the carriage motion has been down, its lower collision edge 10 has then hit bracket 2 and stopped the carriage. Carriage 4 remains stopped as long as the frame is being pulled dow. The carriage is released on pulling belt loop vertically off the rail with respect to the rail.

In normal carriage working position, on pulling belt loop 5 by quite small forces vertically off the rail, the carriage wheel pair 6 is, due to spring 14, the first to touch the rail 1 front edge on both sides of the gap. The carriage moves easily up and down due to rolling of the wheel pair. Further, in this case the carriage is hold by bracket pairs 9, which move parallel with the rail and drag, upon need, along the rail front edge and the inner surfaces of the bent rims 3 in the profile gap but do not disturb the carriage motion to any significant extent.

Figure 4 shows a carriage with an elongated hole 8 for the wheel pair axle and a pin 7 for fixing spring 14. At both carriage ends there are collision edges 10 which hit the brackets 2 upon collision. Further, at both ends of the carriage there is a pair of brackets 9 adjusted to the rail profile 1 so that suit- table clearance is left between their inner surfaces 11 and the inner surfaces of bent rims 3. The rail 1 wall thickness and stiffness is so adjusted that in situations of stress of the rail, due to falling, the rail profile gap can spread out, whereat bent rims 3 take support from the bracket pairs 9 of carriage 4 and prevent further extension of the profile gap. Since the carriage construction takes a portion of the strains on the rail, the rail can be made of quite a thin plate or its walls to a rather thin profile. The front edge as per fig. 2 has

a strong tendency to spread out at the front edge gap, but also other square, circular or combination profiles tend to do the same.

The bracket pairs 9 can be replaced also by wheel pairs if one wants to secure perfect rolling of carriage in the profile front edge. Then the inner flanks of the wheel pairs are adjusted to function with the bent rims 3 and front edges 6 in the same way as parts 9 and their inner surfaces 11.

The invention is not restricted to the embodiment described herein but modifications are possible within the limits of the inventional concept determined in the patent claims.