[0001] The present invention pertains to the field of civil or mining engineering works
where several kinds of machines are used for soil consolidation, drilling, foundation
construction, and the like. More in particular, the present invention refers to an
anti-fall safety device for mounting on machines having heavy loads slidably suspended
on non-horizontal guides. Should one of the sustaining members break, the load is
likely to collapse causing serious damage to people and/or outfits.
[0002] Many soil consolidation machines provide a vertical or inclined tower having guides
on which a carriage is able to slide sustained by cables or chains. Other outfits
that are necessary for the particular function of the machine are mounted on the carriage.
Several series-connected members (cables, chains, tension rods, etc.) sustain the
carriage in the desired position. Breakdown of one of these members may result in
the whole carriage and relevant outfit falling down.
[0003] Safety in known machines at present relies only on correct sizing of the carriage
sustaining members, but no particular arrangement is provided for accidental breaking
of one of such members.
[0004] None of the known commercial apparatuses provide carriage sustaining means disposed
in parallel, i.e. acting simultaneously, nor safety devices capable of being operated
locking the carriage on the tower in case one of the load sustaining members should
break.
[0005] It is an object of this invention to provide a device capable of increasing safety
with outfits having suspended loads slidably mounted on guides.
[0006] It is another object of this invention to provide a device that is activated and
locks the load on the guides at the precise moment of a breaking occurring in one
of the carriage sustaining members.
[0007] These and further objects and advantages, which will be more apparent from the ensuing
description, are attained according to the invention by a device according to claim
1.
[0008] The structural and operational characteristics of two preferred but non-limiting
embodiments of a device according to the invention are described hereinafter with
reference to the accompanying drawings, in which:
- Figure 1
- is a schematic front view of a first embodiment of the device of this invention, mounted
to a carriage which is slidably engaged on a vertical guide;
- Figure 2
- is a schematic side view of the device of Figure 1;
- Figure 3
- is a view, to an enlarged scale, of a detail of Figure 2;
- Figure 4
- is a schematic side view of a second embodiment of the device, different from the
one of Figures 1 and 2; and
- Figure 5
- is a schematic front view of a third embodiment of the device of this invention.
[0009] Referring at first to Figures 1 and 2, numeral 1 indicates overall a conventional
carriage suspended by a sustaining cable 2 and provided with rollers 9 for facilitating
movement along vertical guide 3. Vertical guide 3 forms part of a tower (not shown)
of a soil consolidation or drilling apparatus.
[0010] Carriage 1 has the task of supporting special drilling or soil consolidation outfits
of the apparatus. For simplicity, said outfits are not described hereinafter as being
well known to prior art. However, the outfits are always very heavy mechanical assemblies
to which further units and implements such as tools are attached. For example, a bank
of drilling rods may be attached to a carriage as illustrated of a drilling tower,
the overall weight reached by the carriage/rod bank unit being of several tons.
[0011] According to the invention, the sustaining cable 2 is securely attached at 20 to
the upper end of a piston 11 for maintaining the cable continuously stretched. The
lower end of the piston is pivotally attached to a tension rod 4 that is inserted
in a hole 21 (Figure 3) obtained in a horizontal floating plate 6. Plate 6 is vertically
slidable relative to the tension rod 4 and carriage 1. In normal working conditions,
as shown in Figures 2 and 3, plate 6 is kept steadily at its upper end of stroke,
against an abutment 22 integral with carriage 1. At the lower end of tension rod,
4 a screw nut 7 is tightened against the lower face of plate 6, therefore providing
safe support of the carriage and its implements to the cable 2.
[0012] Moreover, according to the invention, a rigid housing 13 is fixed to the upper portion
of carriage 1. The rigid housing 13 contains a plurality of springs 5 biasing the
upper face of plate 6. The thrust given by the springs is anyway inferior to the weight
of carriage 1 taken alone, so that the floating plate 6 can not be lowered unless
a breaking occurs in one of the supporting elements occurs, as specified more in detail
hereafter.
[0013] Still referring to Figures 1 and 2, the front of plate 6 is fitted with a pair of
opposite outwardly projecting side pins 10 aligned on a common horizontal axis. A
pair of respective cams 8 are pivotally engaged with a certain slack on pins 10. The
back ends 8a of cams 8 are grazing the surface of the guide 3 in normal operational
conditions. The cams 8 are centrally hinged and supported by respective horizontal
and aligned pins 12, which are supported by couples of bearing ears 23 integral with
the carriage 1.
[0014] The operation of the device according to the invention is as follows: as long as
the tensile force with which screw nut 7 holds the plate 6 at its upper end of stroke
prevails on the thrust of springs 5, the anti-fall safety device is not operated.
As soon as this condition no longer persists, due to a breaking occurring in the cable
2 or any other member (the piston 11, tension rod 4, screw nut 7) sustaining the weight
of the carriage and its attached implements, the springs 5 cause the plate 6 to lower
immediately. Consequently. plate 6 pulls the screw nut and the other unloaded supporting
members with it. The pins 10, being pulled downward, rotate cams 8 about their hinges
12 causing cam back portions 8a to engage the guides 3 and stopping the fall of the
carriage 1 in the position it had at the breaking instant.
[0015] Referring to Figure 4, a second embodiment of the device according to the invention
provides the sustaining cable 2 forming a closed ring round pulleys 25, 26 located
at the upper and lower end portions of guide 3, respectively. One end of the cable
2 is secured to a hooking seat 27 located on the bottom part of carriage 1. Further,
the cable 2 is wound around a winch 28 mounted to the back side of the guides, whereby
rotation of the winch in either way causes the carriage to move up or down. In this
different embodiment also, cable tension is constantly provided by the piston assembly
11.
[0016] The embodiment of Figure 4 is ideal for application on machines having tiltable towers
for working in sub-horizontal or inclined directions. The stretched cable 2 holds
the carriage down from the bottom and prevents the springs 5 from releasing untimely
when inclination of the guides produces a lengthwise component of the weight of the
carriage (supported by the cable) inferior to the thrust of compressed springs 5.
[0017] The safety device shown in Figures 1 to 4 is composed by purely mechanical parts.
Figure 5 shows an alternative embodiment of the present invention in which also electrical
and hydraulic components are employed.
[0018] Referring to Figure 5, when one of the above identified failures occurs, the springs
5 bias a lower floating plate 17 downward. A switch 15, located inside housing 13
and connected to plate 17 causes an electric valve 14 to open via a suitable electric
circuit 24 schematically indicated in Figure 5. On either side opposite to guide 3,
the anti-fall device comprises respective locking cams 8 hinged in 16 to the carriage
and similar to those disclosed with reference to Figure 2. The locking cams of Figure
5 are operated by respective hydraulic spring piston assemblies 19, securely attached
to the carriage and fitted with the electric valves 14.
[0019] For a better understanding, the cam 8 on the left in Figure 5 is shown in its passive
or non-operating position grazing the surface of guide 3, while the cam on the right
is illustrated in its active locking position, with its portion 8a engaging the guide.
[0020] When the tensile stress in the sustaining members drops, the springs 55 release and
bias the floating plate 17 downward. The switch 15 operates both electric valves 14
opening them, whereby the pistons 19 are lowered and rotate cams 8 from the initial
non-operational position (shown to the left in Figure 5) to the final working position
(on the right in Figure 5) in which the cams engage the tower guides 3. Consequently,
falling of the carriage is immediately stopped.
[0021] Effective locking of the carriage is provided by cams 8, which are preferably toothed
and made of a material that is harder than the one forming the guides 3. Moreover,
in the locked position, the weight of the carriage further urges the cams on the guide,
thereby further resisting falling.
[0022] It is to be understood that the invention is not limited to the two embodiments herein
disclosed. A further variant (not shown) of the safety device according to the invention
provides an accelerometer as the means for detecting a breaking in the sustaining
members instead of the above discussed spring device. The accelerometer is mounted
to the carriage and connected to the electric valves that empty pistons 19 for operating
them upon detecting a fall of the carriage.
[0023] In a further variant embodiment, the fall-detecting device is formed by an electric
wire disposed parallel to the sustaining cable and connected to the electric valves
14. When a breaking occurs, also the electric wire breaks and automatically activates
the electric valves.
1. A safety device for stopping the fall of a carriage (1) slidably mounted to non horizontal
guides (3) and suspended by a series of tensile stressed sustaining members (2, 4),
characterized in that it comprises means (5) capable of detecting a breaking occurring
in said series of tensile stressed sustaining members (2, 4); said means (5) being
mounted to the carriage (1) and operationally connected to locking means (8) fitted
on the carriage and adjacent the guides (3); said locking means (8) being movable
from a starting non-operational position close to the guides (3) to a final operational
position in which the locking means (8) engage the guides (3), whereby the carriage
(1) is stopped from falling.
2. A device according to claim 1, characterised in that said locking means (8) consist
of cams, hinged (12, 16) to the carriage.
3. A device according to claim 1, characterised in that said means (5) capable of detecting
a breaking occurring in said series of tensile stressed sustaining members consist
of means for detecting tensile stress drops in said sustaining members (2, 4).
4. A device according to claims 1 and 3, characterised in that said detecting means (5)
comprise a plurality of compressed spring means that end to urge downward a plate
(6, 17) suspended to said sustaining members (2, 4).
5. A device according to claim 4, characterised in that said spring means (5) are adjusted
so as to move said plate when the tensile stress in said series of sustaining members
decreases beyond a predetermined value.
6. A device according to claim 4, characterised in that the plate (6) is pivotally mounted
(10) to the cams (8).
7. A device according to claim 4, characterised in that it comprises hydraulic pistons
(19) being linked to said locking means (8); said plate (17) being operationally connected
to hydraulic piston actuating means (14).
8. A device according to claim 1, characterised in that it comprises straining means
(11) mounted to said series of sustaining members (2, 4) for keeping said members
(2, 4) under tensile stress in normal operational conditions.
9. A device according to claim 4, characterised in that one end of said sustaining members
is a cable (2). one end of the cable being bound to a hooking seat (27) located on
the carriage (1), whereby the cable (2) forms a closed ring around pulleys (25, 26)
respectively fitted proximate to the upper and lower ends of the guide (3).
10. A device according to claim 9, characterised in that the cable (2) is wound around
a winch (28) for moving the carriage (1) upwardly and downwardly.