[0001] This invention relates to a device for coupling a pivot to a wheel in wheeled toys,
particularly model automobiles. With particular but not exclusive reference to the
field of model automobiles, such toy automobiles generally have their wheels snap-mounted
onto pivots rigid with the floor of the toy.
[0002] Such a pivot-wheel coupling device is cheap to manufacture and assemble, but it is
also relatively easy to separate the parts. This can be a problem if the child playing
with the model automobile is particularly young because of his known tendency to place
every toy in his mouth. If he places a wheel of the model automobile in his mouth
he needs to exert only minimum force to separate it from its pivot and then swallow
it with the risk of suffocation.
[0003] It is desiderable - and in some countries a legal requirement - that the force which
has to be applied to the wheel to remove it from its pivot is so high as to make it
impossible for a young child to separate the parts.
[0004] For this reason there exist on the market devices for coupling a wheel to a pivot
which make this separation difficult, but which are not totally successful in overcoming
the aforesaid problems.
[0005] The object of the present utility model is therefore to provide a pivot-wheel coupling
device particularly for model automobiles, which offers high resistance to separation
while enabling the wheels to be mounted on their pivots with the same ease as applies
to the coupling devices which are already available commercially.
[0006] These and further objects which will be apparent to the expert of the art are attained
by a coupling device particularly for model automobiles, comprising a pivot rigid
with the automobile floor and having a hempispherical head, and a wheel having a hub
with a frusto-conical bore arranged to receive said pivot, characterised essentially
in that the pivot comprises at the base of a preferably hemispherical head a collar
of trapezoidal cross-section, the wheel comprising a cylindrical cavity into which
the frusto-conical bore of the hub opens, said cavity having a diameter greater than
the forward end of the frusto-conical bore to thus form a step against which the collar
of trapezoidal cross-section abuts when the wheel has been coupled to the pivot.
[0007] The present invention will be more apparent from the accompanying drawing, which
is provided by way of non-limiting example and in which:
Figure 1 is an exploded view from above of a pivot-wheel coupling device for a model
automobile constructed in accordance with the present utility model;
Figure 2 is a section to a considerably enlarged scale on the line II-II of Figure
1.
[0008] With reference to the figures, the model automobile comprises a floor 1 (only partly
shown in Figure 1) carrying pivots 2 for coupling to the wheels of the model automobile.
Figure 1 shows only a portion of the rear end of said floor, from which there extends
a pivot 2 supported by an L-shaped bracket 3. Said pivot extends from that side 4
of said bracket which is orthogonal to the plane in which the floor 1 lies, a stiffening
rib 5 being provided on the rear face of the side 4, which is the opposite face to
that carrying the pivot. The floor 1, pivot 2, bracket 3 and rib 4 are constructed
in a single piece by moulding.
[0009] Starting from the side 4 of the bracket 3, the pivot 2 comrises a shank 6 followed
by a groove and supporting a hemispherical head. At the base of hemispherical head
8 and beyond the groove 7 there is a collar 9 of trapezoidal cross-section.
[0010] Said pivot 2 is arranged to cooperate with a wheel 20 having a hub 1£ from which
ribs 12 extend for stiffening a structure 13 which represents the wheel tyre on the
outside o 14 of the wheel.
[0011] The hub 11 comprises a frusto-conical bore 15 with its vertex opposite a flared mouth
16 into which the hemispherical head of the pivot 2 penetrates. The forward end 17
of said frusto-conical bore 15 opens into a cylindrical cavity 18 coaxial to said
bore and having a greater diameter than said forward end 17 of the bore 15. In this
manner a step 19 is formed, against which the collar 9 of trapezoidal cross-section
rests when the wheel 10 has been assembled on the pivot 8.
[0012] Finally, on the outside 14 of the wheel 10 in proximity to the cavity 18 there is
provided a projecting part 20 with recesses 21, to represent the rim of the wheel
10.
[0013] It will now be assumed that the wheel 10 is to be mounted on the pivot 2. During
this mounting operation, the hemispherical head 8 of the pivot 2 penetrates into the
frusto-conical bore 15 of the hub 11 and compels the collar 9, constructed of resilient
material as are all the other parts described herein, to bend towards the groove of
the pivot 2. When the hemispherical head 8 reaches the cavity 18 and the collar 9
emerges from the forward end 17 of the frusto-conical bore 15, said collar returns
to its initial rest position as it is no longer urged into a bent state, and thus
abuts against the step 19 formed between the cavity 18 and the frusto-conical bore
15. The wheel 10 thus becomes locked on the pivot 2.
[0014] In carrying out the opposite procedure, is to remove the wheel 10 form the pivot
2, the collar 9 encounters the step 19 and provides resistance to removal. As the
pulling force applied to the wheel 10 is increased, said collar 9 bends towards the
hemispherical head in proportion to the applied force until completely reversed, and
only then can the wheel 10 be removed form the pivot 2.
[0015] The described coupling device has high resistance to separation of the parts (more
than 10 kg) while allowing simple assembly of the wheel 10 on the pivot 2 because
of the shape of the collar 9 and the frusto-conical bore 15 through the hub 11.
[0016] The device can be applied, with functional results, in particular to injection moulded
plastics parts of very small diameter and size.
1. A pivot-wheel coupling device for wheeled toys, particularly for model automobiles,
comprising a pivot (2) rigid with the automobile floor (1) and having a preferably
hemispherical head (1), and a wheel having a hub (11) with a frusto-conical bore (15)
arranged to receive said pivot (2), and wherein the pivot (2) comprises at the base
of the head (8) a collar (9) of trapezoidal cross-section, the wheel (10) comprising
a cylindrical cavity (18) into which the frusto-conical bore (15) of the hub (11)
opens, said cavity (18) having a diameter greater than the forward end (15) of the
frusto-conical bore to thus form a step (19) against which the collar (9) of trapezoidal
cross section abuts when the wheel (10) has been coupled to the pivot (2).
2. A device as claimed in claim 1, characterised in that said cylindrical cavity (18)
is coaxial to the frusto-conical bore (15) of the hub (11).
3. A device as claimed in claim 1, characterised in that the pivot (2) extends from
a side (4) of an L-shaped bracket (3) fixed to the floor (1) of the model automobile.
4. A device as claimed in claim 3, characterised in that said side (4) of said bracket
(3) has a rib (5) on the opposite face to that from which the pivot (2) extends.
5. A device as claimed in claim 1, characterised in that the wheel (10) comprises
ribs (12) which extend from the hub (11) to give rigidity to a structure (13) representing
the wheel tyre.