The object of the invention is to provide, for skates with longitudinally aligned wheels, a frame which can be used on irregular surfaces, in particular unsurfaced roads, steps, and generally any surface comprising pronounced irregularities.

A further object of the invention is to provide a skate frame which presents considerable stability. These and further objects which will be apparent from the ensuing description are attained according to the invention by a frame for skates with longitudinally aligned wheels in accordance with claim 1.

Some preferred embodiments of the present invention are described hereinafter with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a skate frame according to the invention; Figure 2 is a plan view thereof, without wheels; Figure 3 is a side view of a second embodiment thereof; Figure 4 shows a different embodiment thereof; and Figure 5 shows it along enlarged transverse section V-V of Figure 4. As can be seen from the figures, the skate frame according to the invention comprises an aluminium or plastic central structure 1 having a substantially inverted-U cross-section and being prolonged at both its ends into two fork-shaped portions 2,3.

A skate boot C (shown by dashed lines on the drawings) is fixed to the central structure 1 on two support surfaces 4 and 5 at different heights. Said

central structure 1 also comprises two holes in its lateral walls 6 for the insertion of pivot pins 7 for two longitudinally aligned wheels 8.

To the arms 9 of both the fork portions 2,3 there are applied further pivot pins T for two wheels 10 of greater diameter and thickness than the two intermediate wheels 8.

The dimensions of the wheels 10 are such that the boot fixing surfaces 4,5 are positioned at a lower level than the wheel upper limit.

The two wheels 10 have a deep grooved tread and are provided internally with an air chamber for better impact absorption. In a modified embodiment the wheels can be formed internally with a spongy material.

The intermediate wheels 8 are constructed of a softer material than the end wheels 10, their purpose being to ensure that in any event the skate rests on the uneven ground, even if considerable roughness is present which could otherwise interfere with the overlying structure 1. From the aforegoing it is apparent that the skate frame according to the invention presents numerous advantages, and in particular: - for the essential support and running wheels, it enables wheels to be used which are of larger dimensions than traditional wheels, and hence more suitable for travelling along irregular surfaces, - as the boot support surface is lower than the upper limit of the end wheels, it results in a lowered centre of gravity, hence providing effective stability. Moreover, as the end wheels are thicker than the intermediate wheels, when travelling along a curve, ie with the skate inclined, ground support occurs only at the edges of the end wheels, with consequent greater ease of curving.

ln a modified embodiment, not shown on the drawings, the intermediate wheels have different diameters to give a different outer appearance to the structure.

In the embodiment shown in Figure 3, rigid with the lower surface of the central structure 1 there is a substantially curved profiled member 11 of antifriction material, in particular plastics, of overall size such that it does not come into contact with the ground when the frame rests on said ground. The purpose of this member 11 is that of protecting the lower surface of the structure expecially when the front wheel has just overcome an obstacle and therefore, being the structure slightly inclined upwards, it is exposed towards said obstacle.

In the embodiment shown in Figure 4, the boot is rigid with a substantially inverted U-shaped plastic structure 12 fixed by transverse pins 13 to the aluminium structure 1 for the wheel 10, which in this case is formed in two equal portions, 1 and 1 ' respectively. Said portions 1 ', 1 " are in their turns connected, through pins 14, to two half-portions 1 1 ', 11 " forming the profiled member.

The central portion 15 of the structure 12 and the central portion 16 of the two frames 1 ',1 " are connected through a vertical pin 17 to which a damping element is coaxially placed, said damping element consisting of a coil spring 18 blocked by a bolt 19.

When the wheels encounter an obstacle, their upward movement causes the half-structures 1 ',11 ' or 1 ",11" to rotate about the pins 13 with respect to the structure 12, with consequent compression of the spring, which discharges the stress received.