Prior art includes frames with front and/or rear wheel assemblies with unsprung axles or structures that link the oscillation of the two wheels in the assembly with inde- pendent suspensions, such as anti-roll bars.

Moreover, existing frames present suspension members de- veloped in height and occupying the usable passenger or freight space, thereby imposing a limited use of the re- spective overlying volume on the part of builders.

In addition, some existing frames consist of pre-formed depressed flatbeds housing the suspension members of the above-mentioned wheel assemblies. Moreover, said flatbeds are not modular and they can be initially constructed only in a very precise size and/or capacity load.

Furthermore, prior art includes frame embodiments that are supporting frames together with the body frame to create a sole, unchangeable structure.

This state of the art is susceptible to remarkable im- provements with a particular focus on the possibility of freeing manufacturers of frames and vehicles from foresee- ing exactly and previously the type of vehicle to be con- structed.

From what has been said so far, the necessity arises of

solving the technical problem of finding a frame configu- ration that can be easily changed and adapted to the spe- cific requirements of the vehicles requested by the end users. Therefore, it is necessary to find a frame and wheel assembly configuration that is capable of taking in- to account the widest and most rigorous standardisation of the component parts themselves.

This invention solves the engineering problem described above by adopting: a modular frame for transportation ve- hicles with a depressed flatbed, including a front wheel assembly with a steering wheel assembly, a rear wheel as- sembly with a fixed wheel assembly, a protruding front structure, a protruding rear structure and a central structure between the wheel assemblies; characterised in that the modular frame presents said structures that can be connected in a rigid way to said wheel assemblies upon assembly with the same type of attachment; there is also a possibility for simultaneous use of a removable connection for the protruding rear structure of the frame on the bus and permanently connections for the other attachments be- tween the wheel assemblies and the respective frame struc- tures.

Adopting, in the preferred embodiment: the central struc- ture of the frame is made up of central beams, lateral box-type beams and intermediate ribs, and equipped with flanges in the wheel assembly attachment area that can be coupled with similar flanges on the wheel assembly to which it have to be rigidly joined.

Adopting, in another preferred embodiment: the protruding front and rear structures of the frame are made up of cen- tral beams, lateral box-type beams, internal transverse members and end transverse members, equipped with flanges in the wheel assembly attachment area that can be coupled with similar flanges on the wheel assembly to which they

have to be rigidly joined.

Adopting, in another preferred embodiment: said wheel as- semblies are made up of a central box-type structure, equipped with raised side parts serving to house the sus- pension connections. In the front and rear attachment ar- ea, the box-type structure is equipped with flanges that can be coupled with similar flanges on the other struc- tures of the frame to which it have to be rigidly joined.

Adopting, in another preferred embodiment: the box-type structure of the wheel assemblies are equipped with at- tachments for the flexible/shock-absorbing elements posi- tioned for the respective suspension; moreover, it presents the housing for the possible driving transmission to the wheels if they are driving wheels.

Adopting, in another preferred embodiment: attachment points are provided for the body parts that have to be connected to the respective part of the frame.

Adopting, in another preferred embodiment: said body at- tachment points consist of a bell connected to the respec- tive frame part and of a corresponding bell-shaped protu- berance fixed to the body part: a flexible element is cen- trally positioned in the coupling, that can be dismanted by a bolt.

Adopting, in another embodiment: the attachment area for connecting the frame structures to the respective wheel assembly consists of flanges arranged longitudinally to the vehicle's axis and interconnected in a rigid way; said flanges project out one towards the other from the respec- tive, opposite transverse members of the wheel assembly and frame structure to be connected.

Adopting, in another preferred embodiment: the supporting body of the wheel assembly stub axles, with uniform con- figuration, differs in application in the driving wheels and/or steering wheels for the suspension and/or transmis- sion attachments.

Adopting, in another embodiment: the suspension attach- ment for the steering wheel is applied on the body and consists of slanted pins inserted in a rigid way on the body itself.

Adopting, in another embodiment: the suspension attach- ment for the fixed wheel is applied on the body and con- sists of specially designed tabs, inserted in a rigid way on the body itself.

Adopting, finally, in an embodiment of a transportation vehicle with a modular frame, characterised by one or more of the preceding parts and in which the motor assembly presents an auxiliary traction motor connected to the transmission and to the combustion engine with a selecta- ble transmission, of one or the other motor or both.

The advantages of this invention include: the composi- tion of the frame parts of the vehicle proves to be more flexible in terms of the adaptation needs required by the end client. The frame in its component parts is assembled only at assembly time, whereas the pre-assembled parts or units can be applied in any case on more than one type of frame, for vehicles with different utilisation needs.

Moreover, the reticulated incorporation of the frame parts allows for lighter weight and change options during assembly with the use of elements in sizes and dimensions suited to the capacity load requirements of the vehicle for which the frame is being built.

In addition, the front and rear wheel assemblies differ only in the specific constitution of the suspension arms, but not in the type of suspension. Both are articulated quadrilateral suspensions, in that the front steering wheel assemblies have the same attachments as the rear, road wheel assemblies, thereby permitting a standardisa- tion of the box-type structure supporting and connecting the other frame parts.

Therefore, the above-mentioned modular structure makes it possible to render damaged body parts replaceable as sin- gle components and also to replace the motor-transmission unit with identical replacement engines to reduce vehicle disuse due to a minimum.

Lastly, even the mechanical parts, the most detailed such as the stub axle casings are built in standard versions for the front, steering and even the rear road wheels, varying only in the suspension attachment with the body itself.

Some embodiments of this invention are illustrated, by way of example, in the six drawing plates enclosed in which: -Figure 1 represents the plan view of the transportation vehicle frame according to the invention, in this case a truck with the engine axis not aligned with the vehicle; -Figure 2 shows an A-A sectional view of Figure 1 serving to show the front axle unit, motorised in this case; -Figure 3 represents the B-B sectional view of Figure 1 representing the intermediate configuration of the frame ; -Figure 4 is the C-C sectional view of Figure 1, with the rear axle unit, idle in this case; -Figure 5 is the plan view of the frame of a transporta- tion vehicle according to the invention, in this case, a bus with an engine transversal to the vehicle and housed in the rear: the sections indicated as A-A, B-B and C-C correspond to the sections appearing in the figures men- tioned previously, when they have been changed to take in- to account a different type of motorization; -Figure 6 shows the side view of the bus fame, also show- ing a further extension of the rear protuberance of the frame yielding an extension in length; -Figure 7 is the side view of the truck frame with an eventual extension of the rear part of the frame;

-Figure 8 shows a different configuration of the truck frame with a greater wheelbase and without the rear protu- berance; -Figure 9 is a partial plan view of a truck with the mo- tor unit housed on the longitudinal axis of the frame ; -Figure 10 is a partial D-D section of the frame shown in Figure 9 also showing a part of one side of the body and its connection to the frame; -Figure 11 shows the plan view of the part of the frame and body appearing in the preceding figure ; -Figures 12 and 13 represent the section, limited to the centre line, of the driving and steering wheel hub on a vertical plane, as well as the varying attachment parts for the suspension arms for an identical hub, but for an idle road wheel; -Figure 14 offers a side view of the box-type structure of the wheel assembly, complete with the suspension at- tachments and other parts of the frame; -Figure 15 represents a perspective view of the attach- ment area between the wheel assembly and a part of the frame, showing the attachment flanges with a riveted or bolted connection.

The following are indicated: 1 in Figure 1, is the mod- ular frame subdivided into five parts, of which 2 is the part with the front protuberance on the vehicle, 3 is the central part and 4 is the part with the rear protuberance; furthermore, 5 is the front steering-wheel assembly and 6 is the rear wheel assembly; in this case the front wheels are the driving wheels, but the frame does not change with the switch in the drive to the rear wheels; 7 indicates the central beams in each part of the frame, equipped with end braces 8 in the vicinity of said wheel assemblies, in the attachment area 9 for the box-type structure 10 of said wheel assemblies, in a transverse member 11 equipped

with a flange 12 in said wheel assembly, and an internal transverse member 13 with flanged ends on said beams 7 and braces 8: said beams and braces are thus coupled in a re- movable way to the above-mentioned box-type structure; 14 indicates the lateral box-type beams on parts of the frame, 15 indicates the front and rear, terminal trans- verse members on the vehicle, 16 the intermediate ribs, 17 the raised part of the box-type structure housing the sus- pension, 18 front, steering or 19 rear, road referring to the respective wheel; 20 represents the flexible, shock- absorbing suspension element; 21 indicates the fulcrum in the steering wheel hubs, while 22 is the hub support for the road wheels ; M is the power unit and T the transmis- sion to wheels; P indicates the driver's seat, while 23 indicates the body structure and frame attachment points.

In addition, the following are also indicated: E, Fig- ure 5, is an electric traction and/or battery-charger mo- tor serving for hybrid functioning of the vehicle, coupled with the combustion engine (M) by means of the transmis- sion (F) with connection selection as desired by the driv- er; R is the change gear which can also be automatic; 24, Figure 10, is the lower carling on the body 25, which in the vicinity of the points 23 features protuberances 26 that are fitted inside said points with the interposition of the flexible bell elements 27 and the respective fas- tening bolt; 28, Figure 12, is the moving support casing for the fulcrums 21 for the steering wheel, or supports 22 for the road wheel, Figure 13, connected with the suspen- sions (18 and 19, respectively) of the respective front 5 and rear 6 wheel assemblies; 29 is the stub axle of the hub of the wheel rotating on said casing with rolling-con- tact bearings; 30 a splined opening for insertion of the axle shaft, if the respective wheel has to be a driving wheel; 31 is the locknut for said rolling-contact bearings

with closure cap for the mouth of the splined 30, when the wheel must remain idle, and 32 is a nut serving only for tightening said bearings, when the axle shaft is inserted in said splined 30; 33, Figure 14, are the attachments for suspension arms in the box-type structure 10,17 in the wheel assembly; 34, Figure 15, are the points of attach- ment of the part of the body on the wheel assembly struc- ture and by 35, identical attachment points, but on the part of the frame that is connected to the wheel assembly: therefore all the attachment points 23 are sub-divided in 34, as part of the respective wheel assembly, and 35, as part of the respective part of the frame connected or con- nectable to the wheel assembly.

Use of the modular design of this invention is de- scribed in the following.

The manufacturers of frames for vehicles build the sim- ilar pieces for the various parts of the frame in bulk and only later, upon assembly, do they perfect the parts re- quired by the specific type of vehicle requested.

The above-mentioned use permits the manufacturer to produce lots at low cost that are much larger than the lots normally produced with a conventional vehicle frame configuration.

Modifications in the vehicle structure are easily planned and carried out by changing the lengths of the frame beams: in this case, for greater frame base or pro- tuberance lengths, larger beam dimensions are foreseen in order to support the greater stress exerted. In the same manner, greater demands on the vehicle in terms of capaci- ty are met by adopting adequate beam dimensions.

Said production of the individual parts in bulk, with- out a specific frame objective, makes it possible to keep in stock the least amount of pieces for those same parts, while the manufacturer is still able to diversify the type

of vehicles to put under assembly rapidly in order to meet the current needs of customers. This also means that there is no need to tie up large sums of money in component parts intended only for one specific use in a certain type of frame.

The practical outcome yields greater flexibility of the production of modular frames with depressed flatbeds ac- cording to the invention, compared to similar frames. The manufacturer can thus invest less capital in the stock of parts making up the frame, with the certainty of being able to use these same parts in all or almost all of the vehicle types proposed for sale and in the least amount of time possible.

The standardisation mentioned above also makes it pos- sible to render the body parts removable from the frame if repairs are needed: the damaged body part can be repaired separately if necessary, while the vehicle can be used in even less time by assembling an identical body part that has been re-conditioned or is new.

In this logic, making the motor unit removable from the vehicle proves to be very convenient for maintenance and/or repair work that may become necessary. For buses this feature is quite beneficial. The motor unit-rear transmission, M, R and T or M, F, E, R and T, can be de- tached from the vehicle frame by directly removing the flanges 12, when they are coupled with bolts, in the re- spective attachment area 9 of the frame part 4 in Figure 5. The maintenance shop can thus make the necessary re- pairs on the motor-transmission unit without keeping the vehicle occupied, for at that same time, they will have assembled an identical motor-transmission unit as replace- ment.

In conclusion, the large-scale production of these same standardised parts allows for rapid replenishment, with

non small quantity lots and thus reduced production costs.

This leads to the synergy of the production of the parts of the vehicle frame, while also maintaining a high level of versatility in terms of the specifications of custom- ers.

If in practice the materials, dimensions and operative details should be different from those indicated, but they technically equivalent, the patent will still apply.