BOOM TRUCK

CAMION A FLECHE

English Abstract

A boom truck which has a cab (4) situated within the chassis (1), a lifting
boom (5) extending from the rear part of the chassis (1),
centrally over the cab, and a device for converting the truck to transport
state with reduced total height in relation to an operating state,
said device having a stand (15) which is pivotable about a lower axis of
rotation (23) at the chassis and supports the lifting boom at an
upper axis of rotation (16), and a rear actuator (26) to turn the stand about
the lower axis of rotation (23), the stand being able to be turned
rearwardly together with the lifting boom (5) while simultaneously lowering
this to a lower level to achieve said transport state. According
to the invention the cab (4) is situated within the central area of the
chassis (1), and said rear actuator is mounted between the chassis and
the stand at a distance from said lower axis of rotation. The device has guide
means (13) to move the cab from its position below the lifting
boom to a free side position outside the lifting boom, the lifting boom being
able to be lowered to a position with its lower side situated
below the level of the roof of the cab.

French Abstract

L'invention concerne un camion à flèche possédant une cabine (4) située dans le châssis (1), une flèche de levage (5) s'étendant depuis la partie postérieure du châssis (1) et passant au-dessus de la cabine de façon centrale, et un dispositif permettant de transformer le camion en mode transport avec une hauteur totale réduite par rapport au mode opérationnel. Ce dispositif possède un montant (15) pivotant autour d'un axe de rotation inférieur (23) au niveau du châssis et porte la flèche de levage au niveau d'un axe de rotation supérieur (16), et un actionneur postérieur (26) permettant de faire tourner le montant autour de l'axe de rotation inférieur (23), le montant pouvant tourner vers l'arrière simultanément avec la flèche (5) tout en abaissant cette dernière jusqu'à un niveau inférieur pour obtenir la position de transport. Selon l'invention, la cabine (4) se trouve dans la zone centrale du châssis (1) et l'actionneur postérieur est monté entre le châssis et le montant à une certaine distance de l'axe de rotation inférieur. Le dispositif possède un moyen de guidage (13) permettant de déplacer la cabine de sa position sous la flèche à une position latérale libre sur le côté de la flèche. La flèche peut être abaissée à une position dans laquelle son côté inférieur est situé au-dessous du niveau du toit de la cabine.

Claims

8
CLAIMS
1. A boom truck comprising a chassis (1), a front pair of
wheels (2), a rear pair of wheels (3), a cab (4) situated
within the chassis (1), a pivotably journalled lifting boom
(5) supporting a lifting unit (6) and extending from the rear
part of the chassis (1), centrally over the chassis (1) and
cab (4) past the front pair of wheels (2), actuators (18) for
turning the lifting boom (5) in vertical plane, and a device
for converting the truck to transport state with reduced total
height in relation to the height in an operating state when
the truck is ready to manipulate a load, the cab (4) being
located vertically under the lifting boom (5) in operating
state of the truck, said device comprising a stand (15) which
is pivotably journalled about a lower axis of rotation (23) at
the rear part of the chassis (1) and extends upwardly from the
chassis (1) to support the lifting boom (5) which is pivotably
journalled at the stand (15) about an upper axis of rotation
(16), and a rear actuator (26) which is arranged on the side
of the stand (15) facing away from the cab (4) to turn the
stand (15) about the lower axis of rotation (23) of said stand
(15), the stand (15) being arranged to be turned in a rearward
direction together with the lifting boom (5) while
simultaneously lowering the lifting boom to a lower level in
order to achieve said transport state, characterized in that
the cab (4) is situated within the central area of the chassis
(1), that said rear actuator (26) is mounted between the
chassis (1) and the stand (15) at a distance from the lower
axis of rotation (23) of the stand (15) on the chassis (1),
and that said device comprises guide means (13) which movably
connect the cab (4) to the chassis (1) to enable movement of
the cab (4) from its position vertically below the lifting
boom (5) to a side position outside the lifting boom (5) and
its said actuator (18) seen in vertical projection, the
lifting boom (5) being arranged by means of said rear
actuator (26) to be lowered to a substantially horizontal
position with its lower side situated below the level of the
roof of the cab (4) in its side position.

9
2. A boom truck as claimed in claim 1, characterized in that
said device also comprises a locking element (30) to lock the
stand (15) in order to prevent the stand (15) from turning
about its axis of rotation (23) in the operating state of the
truck for manipulating loads.
3. A boom truck as claimed in claim 1 or 2, characterized in
that the axis of rotation (23) of the stand (15) on the
chassis (1) is located vertically above the centre axle (22)
of the rear pair of wheels (3).
4. A boom truck as claimed in any one of claims 1 to 3,
characterized in that the axis of rotation (16) of the lifting
boom (5) on the stand (15) is located vertically above the centre
axle (22) of the rear pair of wheels (3) when the truck assumes
its operating state for manipulating load.
5. A boom truck as claimed in any one of claims 1 to 4,
characterized in that the stand (15) comprises two parallel
triangular plates (27, 28) which are journalled on upwardly
directed mounting lugs (29) on the chassis by means of
journalling pins forming said lower axis of rotation (23) and are
situated at one base corner of the stand plates, in that said
actuator comprises two hydraulic cylinders journalled at the top
corners of the stand plates, and in that support elements (24)
are arranged at the base of the stand plates at the other base
corner for cooperation with a similar opposing support element
(25) on the chassis (1).
6. A boom truck as claimed in claim 5 in combination with claim
2, characterized in that the locking device comprises a plurality
of bolts or the like forming screw joints at said support
elements (24, 25).

Description

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The present invention relates to a boom truck comprising a
chassis, a front pair of wheels, a rear pair of wheels, a cab
situated within the chassis, a pivotably journalled lifting
boom supporting a lifting unit and extending from the rear
part of the chassis, centrally over the chassis and cab past
the front pair of wheels, actuators for turning the lifting
boom in vertical plane, and a device for converting the truck
to transport state with reduced total height in relation to
the height in an operating state when the truck is ready to
manipulate a load, the cab being located vertically under the
lifting boom in operating state of the truck, said device
comprising a stand which is pivotably journalled about a lower
axis of rotation at the rear part of the chassis and extends
upwardly from the chassis to support the lifting boom which is
pivotably journalled at the stand about an upper axis of
rotation, and a rear actuator which is arranged on the side of
the stand facing away from the cab to turn the stand about the
lower axis of rotation of said stand, the stand being arranged
to be turned in rearward direction together with the lifting
boom while simultaneously lowering this to a lower level in
order to achieve said transport state.
A boom truck of the type defined above has such a total height
when the lifting boom is in its lowermost, substantially
horizontal position that the truck cannot be driven through
certain low passages where it is desired to transport and
drive the truck. The boom truck therefore has limited use.
The object of the present invention is to reduce this problem
and provide a boom truck that can be easily and auickly
changed to a transport state with reduced total height so than
it can also be driven through low passages with a height
between said two total heights. The boom truck is thus
considerably more useful.
The boom truck according to the invention is characterized in
that the cab is situated within the central area of the

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2
chassis, that said rear actuator is mounted between the
chassis and the stand at a distance from the lower axis of
rotation of the stand on the chassis, and that said device
comprises guide means which movably connect the cab to the
chassis to enable movement of the cab from its position
vertically below the lifting boom to a side position outside
the lifting boom and its said actuator seen in vertical
projection, the lifting boom being arranged by means of said
rear actuator to be lowered to a substantially horizontal
position with its lower side situated below the level of the
roof of the cab in its side position.
The invention will be described in more detail in the
following, with reference to the accompanying drawings.
Figure 1 shows a boom truck according to the invention from
the side, in operating state for manipulating a load.
Figure 2 shows the boom truck according to Figure 1, seen from
above.
Figure 3 shows the boom truck according to Figure 1, seen from
the side in transport state with reduced total height.
Figure 4 shows the boom truck according to Figure 3, seen from
above.
The drawings show schematically a truck of the type generally
termed a boom truck. The truck has a chassis 1, a front pair
of wheels 2 and a rear pair of wheels 3, a driver's cab 4
between the pairs of wheels 2, 3, a long, telescopic lifting
boom S extending centrally above the chassis . from a point
approximately above the rear pai= or wheels 3, past the front
pair of wheels 2 and to a point in front of the front pair of
wheels 2. The lifting boom 5 supports a lifting unit 6 and
comprises a hollow main body or outer boom 7 with rectangular
cross section and an outer telescopic arm or inner boom 8 with
rectangular cross section, protruding from the outer boom 7.
The telescopic arm 8 is L-shaped, having a downwardly directed
*rB

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3
part 9 which at its free end supports said lifting unit 6, the
latter having an engagement body arranged to be set in desired
positions in relation to the lifting boom by means of linear
displacement and turning. Two hydraulic cylinders 10 are
provided for the turning adjustment and are mounted on the
telescopic arm 8 and lifting unit 6 to turn this about a
horizontal shaft 11 located perpendicular to the lifting boom
5. In alternative embodiments the lifting boom has one or more
intermediate telescopic arms. Extension and withdrawal of the
l0 outer telescopic arm 8 in relation to the main body 7 is
effected hydraulically by means of suitable hydraulic
cylinders in the main body 7, and the telescopic arm 8 thus
functions as a piston rod.
A platform 12 is arranged horizontally on the chassis 1
between the pairs of wheels 2, 3. Two parallel rails 13 are
rigidly mounted on the platform 12 and extend perpendicularly
to the longitudinal centre line 14 of the truck. The cab is
provided on its lower side with.two parallel engagement
elements (not shown), which cooperate with the rails 13,
enabling the cab to be moved along the rails. Displacement of
the cab is achieved in controlled manner with the aid of
suitable actuator, e.g. a hydraulic cylinder (not shown). The
rails 13 extend from an inner position on the truck on one
side of said centre line 14 to an outer position on the truck
on the other side of said centre line 14 so that the outer
ends of the rails 13 are situated in line with the wheels on
the relevant side of the truck. The rail and cab arrangement
is thus such that the cab 4 can be set in a first, inner
position in the middle of the truck where the lifting boom 5
is located vertically above the cab 4, and a second, outer
side position on one side of the truck so that no part of the
cab is within the area of the ?_fting boom and its associated
equipment, seen in vertical projection of the lifting boom and
the equipment increasing its width.
The lifting boom 5 is pivotably journalled on a stand 15,
about an axis of rotation 16, the stand being arranged on the
chassis 1 at the rear end of the truck above the rear pair of

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4
wheels 3. The stand 15 extends upwardly a predetermined
distance,from the chassis 1 so that the axis of rotation 16 of
the lifting boom 5 is situated on the stand 15 at such a level
that a small space 17 exists between the cab 4 and the lifting
boom 5 when the lifting boom 5 is in its lowermost, horizontal
position in operating state of the truck, as shown in
Figure 1.
Pivoting of the lifting boom 5 about the axis of rotation 16
is achieved with the aid of two forward hydraulic cylinders
18, the lower ends of which are pivotably journalled on the
chassis 1 or on elements rigidly connected to the chassis, and
the upper ends of which are pivotably journalled on the
lifting boom 5. The lower coaxial journalling shafts 19 of the
hydraulic cylinders 18 are situated vertically above the
centre axle 20 of the front pair of wheels 2, while the upper
coaxial journalling shafts 21 are situated a predetermined
distance from the axis of rotation 16 of the lifting boom on
the stand 15 in order to provide sufficient lifting capacity.
2o These journalling shafts 21 are normally situated above a
central region of the truck seen in the lowermost horizontal
position of the lifting boom 5 when the truck is in operating
state as shown in Figure 1. The hydraulic cylinders 18 thus
form an acute angle, such as 40-50°, with the horizontal
plane.
In operating state of the truck according to Figure 1, the
axis of rotation 16 of the lifting boom 5 on the stand 15 is
situated vertically above the centre axle 22 of the rear pair
of wheels 3, this centre axle being perpendicular to the
centre line 14 of the truck.
The stand 15 is pivotably journalled on the chassis above a
lower axis of rotation 23 which is stationary and situated
vertically above the centre axle 22 of the rear pair of wheels
3, and thus vertically below the axis of rotation 16 of the
lifting boom 5 on the stand 15 when the truck is in its
operating state for manipulating a load. The stand 15 is
extended forwards to the cab and is provided on the extended

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part with support elements 24 cooperating with corresponding
support elements 25 on the chassis 1 in the operating state of
the truck. Part of the load from the lifting boom 5, the
lifting unit 6 and any load being carried, is transferred to
5 the chassis 1 via these support elements 24, 25. The support
elements 24, 25 are situated at a predetermined distance from
and in front of the axis of rotation 23 of the stand 15 on the
chassis 1. The distance is suitably about 40-60% of the
distance between said two upper and lower axes of rotation
16, 23.
On the side of the stand 15 facing away from the support
element 24 there are two hydraulic cylinders 26, the lower
ends of which are pivotably journalled on the chassis 1 at a
predetermined distance from the axis of rotation 23 of the
stand 15 and the upper ends of which are journalled on the
stand 15 at its upper part in the vicinity of the axis of
rotation 16 of the lifting boom 5 on the stand 15. The
hydraulic cylinders 26 have a stabilizing effect on the stand
15 when this is turned about its axis of rotation 23.
In the embodiment shown the stand 15 comprises two parallel,
generally triangular plates 27, 28, resembling link arms,
which are situated one on each side of the lifting boom 5 and
are pivotably journalled on coaxial journalling pins forming
said lower axis of rotation 23. Said support element 24 of the
stand 15 is formed by a flat support element on each stand
plate 27, 28, situated at the inner corner of the support
plate 27, 28 and at its base, the chassis 1 being provided
with a corresponding support element. Each of the two rear
hydraulic cylinders 26 is connected to a stand plate 27, 28 in
the vicinity of its upper corner which also constitutes the .
journalling point for a journalling pin, these coaxial
journalling pins forming the axis of rotation 16 of the
lifting boom 5 on the stand. Each stand plate 27, 28 is
pivotably journalled by means of journalling pins on mounting
lugs 29 extending upwardly from the chassis, said coaxial
journalling pins forming said lower axis of rotation 23 of the
stand 15 on the chassis 1.

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The arrangement also includes a locking device 30 for locking
the stand 15 to the chassis 1 when the truck assumes operating
state to manipulate a load. In the embodiment shown this
locking device comprises suitable screws arranged at said
support elements 24, 25 to form a detachable screw joint. The
locking device may be of any type that provides the desired
locking function with maximum safety. It may also include one
or more hydraulic locking devices, suitably spring loaded, so
l0 that locking position is always assumed by a suitable locking
element, e.g. a locking wedge, even if the hydraulic system is
out of action for some reason.
The truck is arranged to be changed to transport state as
shown in Figures 3 and 4 when desired. In this state the truck
has reduced total height in comparison with the lowest height
the truck has in its operating state as shown in Figure 1. The
first measure taken is for the cab 4 to be moved from its
central location to its side location on the truck, in which
it is situated outside a vertical projection of the lifting
boom and the hydraulic cylinders 18 with associated mounting
equipment at the sides. The locking device 30 is then released
so that the stand 15 can be turned freely backwards. The rear
hydraulic cylinders 26 are then activated to retract their
piston rods, at the same time as the hydraulic cylinders of
the lifting boom are activated to press out their piston rods.
The hydraulic cylinders 18 of the lifting boom 5 will thus
displace the lifting boom 5 backwards at the same time as the
hydraulic cylinders 26 of the stand 15 pull the stand 15
backwards and downwards, and the support elements 24 of the
stand 15 leave the support elements 25 of the chassis 1. The
stand 15 is turned about its lower axis of rotation 23 and the
axis of rotation 16 of the lifting boom 5 will thus describe a
circular arc. The lifting boom 5 will then assume a horizontal
position with its upper side on a level with the roof of the
cab 4 or just above it, e.g. less than 10 cm and preferably
less than 5 cm above the roof. In general, therefore, when the
truck is in transport state the lower side of the lifting boom
is situated beneath the level of the roof of the cab, which is

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now in its side position, whereby the distance between the
lower side of the lifting boom and the level of the roof may
be equivalent to the thickness of the lifting boom (which may
be 40-80 cm, for instance? in vertical direction, seen in the
transport state of the truck, or somewhat less than this
according to the above values. The total height of the truck
has thus quickly been considerably reduced and the truck can
thus pass through low passages to spaces not previously
accessible to this type of truck.
l0
20
30

Representative Drawing