AU2005239635B2 - A vehicle for supporting a load on a chassis - Google Patents

Abstract

A transport truck 10 is disclosed that comprises a chassis 12 having at least two 5 front and two rear wheels mounted thereon towards respectively a front 14 and a rear 16 thereof. The chassis 12 also includes a pair of laterally spaced chassis rails 30, 32 extending longitudinally towards a rear of the chassis 12. The truck 10 has a support 13 mounted on the chassis rails 30, 32. The support 13 comprises a horizontally extending sub-frame 35 and a barrel 10 supporting frame 80 extending up from the sub-frame 35. An important feature is that the barrel supporting frame 80 can pivot relative to the sub-frame 35 including support rails 37, 38 and/or the chassis rails 30, 32. The truck 10 also includes a rotatable barrel 15 mounted on the support 13 above the chassis rails 30, 32, the barrel 15 being oriented on its side with its axis extending 15 broadly horizontally. The barrel 15 has a track ring 20 and the barrel 15 is supported on the track ring 20 by the trunnion rollers 90, 92 at the top of the barrel supporting frame 80. The support 13 also has transverse rollers 95, 96 bearing up against a surface of the track ring 20 to align the rear support members longitudinally in the correct position on the support 10. The 20 combination of the pivoting of the barrel supporting frame 80 and the transverse rollers 95, 96 gives the support 13 more flexibility and enables it to move with chassis rails 30, 32 that bend and reduce the stresses being transferred to the support by bending of the chassis rails. 10 20 4/8 15 40, 16 50 52 12 70 42 14 0\ 96 37-

Description

1 A VEHICLE FOR SUPPORTING A LOAD ON A CHASSIS FIELD OF THE INVENTION 5 This invention relates to a vehicle for supporting a load on a chassis. This invention relates particularly but not exclusively to a vehicle that is a concrete transport truck having a rotatable barrel mounted on its chassis that is used to carry a load of cementitious material, e.g. concrete. It will therefore be 10 convenient to hereinafter describe the invention with reference to this example application. At the same time, it is to be clearly understood that the invention is capable of broader application. For example, the invention could be applied to vehicles for carrying heavy loads other than concrete transport trucks. For instance, it could equally be applied to trucks that have bins for carrying heavy 15 loads, such as loads of particulate material. Such trucks are used extensively in earth moving, building and mining applications. BACKGROUND TO THE INVENTION Cement and concrete are widely used building and engineering materials. They 20 can be used in buildings, walls, bridges and the like. The concrete or cement is mixed up in concrete mixing plants and then batches of the material are transported to the building site where they will be used. The cement and concrete needs to be handled in a special way to resist its tendency to set when it is transported from the mixing plant to the building site. 25 Over time, a technology has evolved whereby concrete transport trucks are used to transport batches of the material from the plant to the building site. Such trucks have the ability to constantly turn the material they are carrying, to resist it from setting. An example of a prior art concrete truck that is in use in 30 Australia is shown in Fig. 1.

2 Such a vehicle is typically a large prime mover with a cabin and an engine at the front. A chassis is mounted on wheels and the chassis extends rearward from the cabin. 5 Typically the chassis includes two spaced rails made of steel that extend from a forward region of the prime mover to the rear thereof. The two laterally spaced rails are joined together by a plurality of cross braces at spaced intervals along the length of the rails to form a structure. The cross members help to stiffen and brace the structure. The chassis rails may also include gussets to further brace 10 and strengthen the chassis. A barrel for receiving and holding the concrete to be transported is mounted on the chassis and this is driven to rotate by a drive means that may be a hydraulic motor. The barrel is orientated on its side with a substantially horizontal axis. A 15 front end of the barrel is closed and the rear end of the barrel is open. The barrel might typically have a diameter of 2m, a length of 4m and have an internal volume of 5 - 8m . The barrel is made of steel or other material or composite and is a heavy structure on its own. This weight is substantially increased when the barrel is full of concrete, which has a specific gravity of 2.35 20 - 2.55. The barrel and load of concrete may have a collective weight of about 15-18 ton. While in use transporting concrete or cement from the plant to a site, the barrel rotates continuously. This constantly turns the cement to keep it from 25 segregating and helps retard and delay setting of the material while being transported to site. A support in the form of a support frame assembly supports the barrel in position spaced above the chassis. The support frame assembly needs to be 30 sufficiently strong to carry the static weight of the barrel and its load. It also needs to be able to accommodate the additional stresses and strains imposed when the truck is driven along a road that is not perfectly even.

3 These additional stresses and strains were not of great concern about 10 - 15 years ago. At this time the chassis of a concrete transport truck would have been made out of high gauge steel that was very thick and as a result, also very strong. 5 Further, at this time concrete transport trucks were fitted with traditional leaf springs, or rubber block suspensions. These provided a relatively hard ride for the driver but they did not flex excessively and thus, did not impart an unduly high level of stress to the chassis rails and the support frame assembly. 10 However, in more recent times and particularly the last 5 years, there has been a steady reduction in the gauge and thickness of the steel used to form the chassis rails due to increased strength of the steel used. As a result, the chassis rails are much lighter and thinner than they were 10 years ago as 15 described above. The advantage of this development is that the vehicle can carry a correspondingly larger load of concrete. However, the downside is that the chassis rails and cross members are not as rigid as they used to be. However, in addition, in recent times many of the concrete transport trucks have 20 been fitted with air bag suspensions instead of leaf springs, or rubber block suspensions. The air bag suspensions provide a softer ride with more movement of the chassis than with rubber block suspensions. The reason air bag suspensions are being chosen nowadays is that they provide a considerably softer ride for the driver and in addition, they reduce wear and tear 25 on the truck. A yet further reason for the increased uptake of air bag suspensions is these suspensions are considered by road authorities, in Australia at least, to be less hard on the road and less likely to damage the road. As a result, it is possible 30 for an owner to apply for a weight concession that enables them to carry a correspondingly greater load of concrete on the truck each time it is used. It will readily be appreciated that the ability to carry a greater load rapidly translates into a financial advantage. As a result, it has become very popular for these 4 trucks to be fitted with air bag suspensions and this could almost be considered to be the norm these days. However, a downside of an air bag suspension is that it results in a lot more 5 movement in the chassis than with the usual rubber suspension. Further, the narrow gauge of steel used for the chassis rails further exacerbates the movement and bending of the chassis rails when it is conveying a full load of concrete during travel of the truck on the road. The typical movement that a chassis on a concrete transport truck undergoes is shown in Fig 2 of the 10 drawings, which omits the barrel for the purpose of clarity and also Figs 3 and 4. Currently this increased movement and flexing of the chassis rails is transmitted through to the support frame assembly supporting the barrel in position spaced above the chassis. The support frame assembly is an essentially rigid structure 15 and this movement, or tendency to move, will result in forces being transmitted through to the support frame assembly and result in high forces being applied to the various component members of the support frame assembly. Over time, the members of the support frame assembly will become fatigued as 20 a result of these additional stresses. This fatigue over time will lead to the failure of a said member. In fact, Applicant has observed and noted that these support frame assemblies are cracking and failing in a substantially shorter time than that which occurred previously, i.e. when the chassis rails were thicker and more rigid and air bag suspensions were not used. 25 When the support frame assembly fails it needs to be repaired or replaced. This entails vehicle down time and also the repair is costly as the entire support frame assembly needs to be replaced. A further risk is that the support frame assembly may fail catastrophically while the truck is in use. This poses a safety 30 risk to the driver as well as other users' of the road. With the threat of civil litigation and criminal charges ever present, this poses an unacceptable level of risk for many companies that operate concrete transport trucks.

5 Clearly, it would be advantageous if a way could be found of reducing the high level of forces transmitted through to the support frame assembly as a result of more flexible chassis' and air bag suspensions. This would extend the working life of the support frame assembly and also reduce the risk of catastrophic s failure of the chassis. SUMMARY OF THE INVENTION According to one aspect of his invention there is provided a transport truck 10 having a rotatable mixer barrel that rotates about a broadly horizontal axis, the truck comprising: a chassis including a pair of laterally spaced left and right chassis rails extending in a longitudinal direction; a barrel having a front and a rear that rotates about an axis extending 15 broadly in the longitudinal direction; a front barrel support mounted on the chassis rails comprising a substantially rigid front barrel support frame that is substantially rigidly mounted on the chassis rails which supports the front of the barrel in a way that enables the barrel to rotate on the front barrel support and enables a barrel drive 20 arrangement to be driveably coupled to the front of the barrel; and a rear barrel support including a rear barrel support frame mounted on the chassis rails and supporting the rear of the barrel spaced above the chassis rails in a way that enables the barrel to rotate, the rear barrel support frame being able to pivot in a longitudinal direction relative to the chassis to adjust for 25 deformation of the chassis rails in a longitudinal direction. The rear barrel support frame may include at least one longitudinal support formation that acts against a rearward facing surface of the barrel to retain or stop the barrel in a longitudinal direction. 30 The at least one longitudinal support formation may comprise at least one roller that is positioned so that it can run over a rearward facing surface of the barrel. In particular the at least one longitudinal support formation may comprise two 6 laterally spaced retaining rollers that are positioned to roll over a rearward facing surface of the track ring. The transport truck may further include a rear sub-frame which is mounted on 5 the chassis rails towards the rear thereof, and each support post may be mounted on the rear sub-frame, at or towards its lower end, by means of a pivotal mounting whereby to enable the rear barrel support frame to pivot in a longitudinal direction. 10 The rear barrel support frame may comprise two upright support posts that extend up from the rear sub-frame on which the barrel is supported. The rear barrel support frame may further include at least one cross member extending between the support posts, e.g. an upper cross member towards 15 upper ends of the support posts and a lower cross member towards lower ends of the support posts. Each support post may be mounted on the rear sub-frame, at or towards its lower end, by means of a pivotal mounting whereby to enable the rear barrel 20 support frame to pivot in a longitudinal direction. The pivotal mounting may include a bearing, e.g. a spherical bearing that can rock from one side to another as well as pivot forward and rearward. 25 The rear barrel support may further include at least one vertical support formation which supports the rear end of the barrel and over which the barrel rotates mounted on top of the rear barrel support frame, e.g. on the upper cross member thereof. 30 The barrel may include a track ring extending circumferentially around the barrel, and the vertical support formation may include two laterally spaced rollers over which the track ring rolls. Optionally the two laterally spaced rollers may be mounted on the upper cross member.

7 The front barrel support may include a front sub-frame mounted on the chassis rails towards the front thereof, and the front support frame may be substantially rigidly mounted thereon. 5 The front sub-frame and/or the rear sub-frame may include two longitudinal sub frame rails which are mounted to the left and right chassis rails respectively. The two longitudinal sub-frame rails may be mounted directly on top of the left 10 and right chassis rails and may be fixed to the chassis rails by means of vertically extending chassis attachment elements that extend across the associated sub-frame rail and the chassis rail. The front sub-frame and/or the rear sub-frame may further include at least one 15 cross frame extending between the longitudinal sub-frame rails. According to another aspect of this invention there is provided a vehicle comprising: a chassis including a pair of laterally spaced chassis rails extending in a 20 longitudinal direction having a front end and rear end; a load having a front and a rear; a front load support mounted on the chassis rails comprising a substantially rigid front load support frame that is substantially rigidly mounted on the chassis rails which supports the front end of the load; and 25 a rear load support including a rear load support frame mounted on the chassis rails and supporting the rear end of the load spaced above the chassis rails, the rear load support frame being able to pivot in a longitudinal direction relative to the chassis to adjust for deformation of the chassis rails in a longitudinal direction. 30 The vehicle may include any one or more of the features of the transport truck defined in the first aspect of the invention.

8 According to yet another aspect of this invention there is provided a transport truck having a mixer barrel that rotates about a broadly horizontal axis, the truck comprising: a chassis including a pair of laterally spaced chassis rails extending in a 5 longitudinal direction having a front end and rear end; a barrel having a front and a rear that rotates about a substantially horizontal axis; a front barrel support mounted on the chassis rails comprising a substantially rigid front barrel support frame that is substantially rigidly mounted 10 on the chassis rails which supports the front end of the barrel in a way that permits it to rotate on the front barrel support and also permits a barrel drive arrangement to be driveably coupled to the barrel; and a rear barrel support mounted on the chassis rails, the rear barrel support including a rear barrel support frame comprises two upright support 15 posts extending up from the chassis rails and at least one cross member extending between the upright support posts towards their upper ends, the rear barrel support frame supporting the barrel in a way that enables the barrel to rotate, and the rear barrel support including a pivotal mounting including a universal bearing that can rock from one side to another as well as pivot forward 20 and rearward, that enables the rear barrel support frame to be able to pivot in a longitudinal direction relative to the chassis to adjust for deformation of the chassis rails in a longitudinal direction. The rear barrel support frame may include at least one longitudinal support 25 formation which acts against a rearward facing surface of the barrel to retain or stop the barrel in a longitudinal direction. The at least one longitudinal support formation may comprise at least one roller that is positioned such that it can run over a rearward facing surface of the 30 barrel. The transport truck may include any one or more of the features of the transport truck defined in the first aspect of the invention.

9 According to another aspect of this invention there is provided a vehicle for supporting a load on a chassis, the vehicle comprising: a chassis on which a plurality of ground engaging formations are 5 mounted; a support mounted on the chassis and extending upward therefrom, the support comprising a sub-frame that lies across the chassis and is fixed thereto, and a load support frame that extends up from the sub-frame for supporting a load above the sub-frame, the load support frame being pivotally mounted to 10 the chassis, or the sub-frame, by means of at least one pivotal mounting whereby to permit the load support frame to pivot to some extent relative to the sub-frame and chassis. The load support frame may be pivotally mounted to the sub-frame, i.e. as 15 distinct from the chassis. The load support frame may be pivotally mounted to the sub-frame by means of two laterally spaced pivotal mountings, e.g. pivotal mountings on each of left and right sides of the sub-frame. The pivotal mountings may be positioned towards the rear of the sub-frame and/or the chassis, e.g. right at the rear of the sub-frame. In turn, the sub-frame may be 20 mounted on and attached to the chassis. Each pivotal mounting may pivot about a transverse axis i.e. that is parallel to the axis of wheels of the vehicle and transverse to the longitudinal axis of the vehicle. 25 Thus, the sub-frame of the support lies flat across the chassis rails and the load support frame extends up from the sub-frame. The upwardly extending load support frame can pivot to some extent relative to the sub-frame and this enables it to rock on the sub-frame. This then enables it to accommodate 30 bending in the chassis, particularly towards its rear, e.g. when the vehicle goes over bumps, or the like, by pivoting slightly relative to the chassis and associated sub-frame. The sub-frame is mounted in a fixed position on the chassis and does not move to any appreciable extent relative thereto.

10 The load support frame may comprise a pair of laterally spaced load support posts extending up from the sub-frame. Each said post may be broadly positioned at the rear of the sub-frame. Each post may be located just laterally 5 inward of the side of the sub-frame. Thus, the load support posts effectively carry the weight of the load above the support frame. The load support frame may further include at least one load supporting frame cross member extending between the two posts. The load support frame may 10 include two said load supporting frame cross members that are vertically spaced from each other, one being an upper load support frame cross member and the other being a lower load support frame cross member. The chassis may comprise two laterally spaced longitudinally extending chassis 15 rails. The sub-frame may also comprise two laterally extending longitudinally spaced support rails, one said support rail being mounted on one of the chassis rails and the other support rail being mounted on the other said chassis rail. Each pivotal mounting may comprise a rod or pin that is mounted to one of the 20 sub-frames and the upwardly extending load support frame and a sleeve surrounding the rod that is mounted to the other of the rod and sub-frame. Conveniently the rod may be mounted on the sub-frame and the sleeve may be mounted to the upwardly extending load support frame, e.g. rigidly. 25 The pivotal mounting may also include a bearing sandwiched between the sleeve and the rod. The bearing enables the sleeve to be vertically supported by the rod while still permitting the sleeve to pivot, e.g. freely, relative to the rod. The bearing may be a spherical bearing. This enables the bearing to tilt or rock from side to side as well as rock forward and rearward. This feature is useful 30 because it enables the vehicle to accommodate lateral or twisting movement in the chassis rails as well as longitudinal bending of the chassis rails.

The sleeve may be mounted to a post of the upwardly extending load support frame. The rod may be mounted to a member of the sub-frame that extends in a 5 longitudinal direction. The member of the sub-frame to which the rod is mounted may be a said support rail, or an extension of the support rail. The rod may be mounted on two spaced plates, one said plate being formed by an extension of the support rail and the plates may be spaced in a lateral 10 direction. The spaced plates may define apertures therein. The rod may pass through the apertures defined in the spaced plates to hold the rod in its position relative to the plates. The rod or pin may not be positively attached to the spaced plates, 15 e.g. so that it can adjust relative thereto. This helps to reduce the level of stress transferred from the chassis to the support, in this case the sub-frame of the support. The spaced plates may be positioned over each end of the sleeve and hold the 20 sleeve in position, i.e. between the plates. The end plates are welded to the sub-frame, e.g. a cross plate underneath the spaced plates. The pivotal mounting further including a spacer between at least one plate and the bearing to pack the bearing in position in the mounting. 25 The pivotal mounting may further include a locking pin that is passed through an opening defined in the rod towards its inner end. The locking pin is mounted on the rod so that it cannot be pulled out of the openings in the plates to hold the rod in position on the sub-frame. Thus, the rod is not positively fixed to the 30 spaced plates and is held retained in position by the locking pin. Each chassis rail may be attached to the sub-frame by at least two longitudinally spaced points along its length. Thus, each support rail may be 12 mounted on the associated chassis rail at least two points, e.g. such that they are held together do not move appreciably relative to each other. The vehicle may include chassis attachment elements for attaching the chassis 5 rail to the associated support rail at each of the longitudinally spaced positions of attachment. Each support rail may be mounted on the associated chassis rail by means of a rear chassis attachment element extending between the support rail and the 10 associated chassis rail towards the rear of the chassis rail; and a forward chassis attachment element also extending between the support rail and the associated chassis rail forward of the rear attachment element. Each forward chassis attachment element may be rigidly attached to both the 15 chassis rail and the support rail by means of a plurality of bolts passing through the attachment element and the chassis, or support rail, as the case may be. The rear chassis attachment element may be attached to the chassis rail in the manner described above, e.g. by having a plurality of bolts passing through the 20 element and the rail. The rear chassis attachment element may be attached to the support rail by being attached to the rod for the pivotal mounting. This is therefore different to the other points of attachment of the chassis attachment elements. The rod is 25 attached, e.g. positively, to the chassis attachment element at one end and is then passed through the spaced plates. A transverse locking pin is passed through the rod towards its end remote from the chassis attachment element, which prevents the rod from being pulled off the plates. Thus, the rod is attached to the chassis attachment element and moves with it but the rod can 30 adjust relative to the sub-frame. Each support rail may extend forward from a rear end proximate to the rear of the chassis rails to a position forward of the rear of the chassis.

13 In one embodiment of the invention referred to as the short sub-frame embodiment, each support rail may extend only a short length forward from the rear of the chassis and does not extend the full length of the chassis rails. In 5 this embodiment the support may include further separate body support rails towards the front of the chassis. In another embodiment of the invention called the long sub-frame embodiment, each support rail may extend substantially the full length of the chassis such 10 that the front ends of the support rails are proximate the front ends of the chassis rails behind the vehicle cab. The sub-frame may further include at least one longitudinally spaced cross member interconnecting the two laterally spaced support rails and the rails and 15 the cross member may be rigidly connected to each other to form a sub-frame. In the short sub-frame form of the invention, the sub-frame may have at least one cross member towards the rear of the support rails. The vehicle may further include a load mounted on the support spaced above 20 the chassis and the load supporting frame may further include one or more load engaging formations mounted on a relatively upper said load supporting frame cross member for physically carrying the load supported on the vehicle. The load engaging formations may include one or more vertical formations for 25 supporting the load in a vertical direction. The load engaging formations may also include one or more longitudinal formations for supporting the load in a longitudinal direction. More specifically, the longitudinal formations may be positioned behind the load and resist displacement of the load in a rearward direction. 30 In one form, the vertical formations may comprise trunnions, e.g. a pair of trunnions, positioned underneath the load that supports a load that rotates on 14 the support. In one form, the longitudinal formations may comprise transverse rollers, e.g. a pair of rollers that sit behind the load. The ground engaging formations may be wheels, e.g. a set of front wheels and 5 a set of rear wheels. According to another aspect of this invention, there is provided a transport truck having a barrel that rotates about a broadly horizontal axis, the truck comprising: 10 a chassis having at least two front and two rear wheels mounted thereon towards respectively a front and a rear thereof, the chassis comprising a pair of laterally spaced chassis rails extending longitudinally towards a rear of the chassis; a support comprising a horizontally extending sub-frame mounted on the 15 chassis rails and a barrel supporting frame extending up from the sub-frame, the load support frame being pivotally mounted to the chassis or the sub-frame by means of at least one pivotal mounting whereby to permit the load support frame to pivot to some extent relative to the sub-frame and chassis; and a rotatable barrel mounted on the support above the chassis rails, the 20 barrel being oriented on its side with its axis extending broadly horizontally. The sub-frame may comprise a pair of laterally spaced support rails and the barrel supporting frame extending up from the sub-frame may comprise two laterally spaced barrel support posts. 25 Thus, the barrel support frame can be pivoted relative to the sub-frame, e.g. the support rails and/or the chassis rails to accommodate bending of the chassis rails, particularly towards the rear thereof. The angle or attitude of the posts can adjust to accommodate the bending of the chassis rails so that the tendency of 30 the chassis rails to bend does not transmit high levels of force back through the support and particularly the posts of the barrel support frame.

15 Each said support post may be pivotally mounted to the sub-frame, e.g. indirectly, towards the rear of the sub-frame and also the rear of the chassis rails. 5 Each pivotal mounting may comprise a rod mounted to one of the sub-frame and the barrel support frame and a sleeve circumferentially surrounding the rod and capable of pivoting thereto mounted to the other of the sub-frame and the barrel support frame. 10 Conveniently the rod may be mounted to the sub-frame, e.g. the support rail or an extension thereof and the sleeve may be mounted to the barrel support frame, e. g. the post. The barrel support frame may include at least one barrel support cross member 15 extending between the barrel support posts. The barrel support frame may include an upper said barrel support cross member that extends between the barrel support posts towards the upper ends of the barrel support posts. The barrel support frame may also include a lower 20 barrel support cross member that extends between the barrel support posts towards the lower ends thereof. Each support rail may be attached to its associated chassis rail in at least two longitudinally spaced positions by means of chassis attachment elements. Each 25 chassis attachment element may extend across both the support rail and the chassis rail, e.g. on the outside thereof and attached to both the support rail and chassis rail. A rear chassis attachment element may extend between the support rail and the 30 associated chassis rail towards the rear of the chassis rail and a forward chassis attachment element may also extend between the support rail and the associated chassis rail forward of the rear attachment element.

16 Each forward chassis attachment element may be rigidly attached to both the chassis rail and the support rail by means of a plurality of bolts passing through the attachment element and the chassis, or support rail, as the case may be. These attachments are clearly rigid and permit no pivoting of the components 5 relative to each other. The rear chassis attachment element may be attached to the chassis rail in the manner described above, e.g. by having a plurality of bolts passing through the element and the rail. 10 The rear chassis attachment element may be attached to the support rail by having the rod for the pivotal mounting attached to the chassis attachment element, or integral therewith and passing through an opening in the support rail. This is therefore different to the other points of attachment of the chassis 15 attachment elements. This confers on the sub-frame an ability to adjust the support rails relative to the chassis. The attachment of the support rails to the chassis rails may include any one or more of the features, including optional features described above according to 20 the first aspect of the invention. By virtue of the fact that the sub-frame rail lies over the chassis rail in contact therewith, the two rails cannot move appreciably relative to each other. 25 Each pivotal mounting may also include a bearing interposed between the rod and the sleeve to permit the rod and sleeve to pivot relatively freely in relation to each other. The bearing may be a spherical bearing that is capable of movement in three dimensions. This enables the posts to rock to some extent from forward to aft as the bearing may include any one or more of the optional 30 features of the bearing described above, according to the first aspect of the invention. Movement of any type by the chassis does not result in stresses being transferred to the support frame.

17 The sub-frame may include at least one sub-frame cross member extending between the support rails. In one form, the sub-frame may have one said sub frame cross member extending between the support rails towards the rear of the support rails. 5 Similarly, the chassis may further include at least one cross member extending between the chassis rails. Conveniently there may be a number of chassis cross members at spaced intervals along the length of the chassis rails. 10 The barrel may include a track ring extending around its circumference on its outer surface and the track ring may be positioned towards the rear of the barrel. The barrel support frame may further include at least one barrel support 15 formation mounted on the upper barrel support cross member that physically supports the barrel. The barrel support formation/s may include at least one vertical barrel support formation and at least one longitudinal support formation. The at least two 20 vertical barrel support formation may include a trunnion roller mounted positioned underneath the track ring on which the track ring runs to support the barrel towards its rear, while permitting it to rotate. The at least one vertical barrel support formation may comprise two said 25 trunnion rollers mounted on said barrel support cross member that are laterally spaced apart from each other being captured by the track ring. The at least one longitudinal barrel support formation may include at least one transverse roller mounted on said barrel support cross member that is rearward 30 of the track ring and is positioned to roll over a vertically extending rear surface of the track ring to resist any rearward displacement of the barrel during operation of the vehicle. The barrel support formation may comprise at least two said transverse rollers, one said transverse roller being positioned in proximity 18 to one of the trunnion rollers and the other being positioned in proximity to the other trunnion roller. Each transverse roller may be oriented to extend parallel to the vertically 5 extending rear surface of the track ring at the point at which it engages and runs over said rear surface. The transverse rollers help to hold the barrel support frame in its correct longitudinal position, bearing in mind the pivotal mounting of the barrel support 10 frame to the sub-frame permits increased flexibility of the support. The sub-frame may be a short sub-frame that extends only part of the distance from the rear of the chassis towards the front of the chassis. In such a case, the support may include a further separate sub-frame located towards the front is of the barrel. This further sub-frame may be rigidly mounted to the chassis rails by means of at least two longitudinally spaced chassis mounting elements. Each of the front chassis mounting elements may be rigidly mounted to both the further sub-frame and the chassis rails. Thus, this sub-frame does not have any pivotal mounting like the one towards the rear. 20 The transport truck may be a concrete or cement transport truck and the barrel may be capable of carrying a load in excess of 10 tons. The truck may be a commercially available truck having an air bag suspension and having a pair of spaced chassis rails and the support and barrel may be custom built and 25 mounted on top of the chassis rails. The barrel support frame may pivot in the range of 1 degree to 20 degrees, e.g. 1-10 degrees. It pivots just enough to accommodate bending of the chassis rails towards the rear. 30 Further, there is only one longitudinal position where pivoting takes place and this is towards or at the rear of the chassis. The load support frame and in particular the barrel support posts at the rear are pivotally mounted to the sub- 19 frame and the chassis rails. Only small amounts of pivoting action take place forward of this point. The forward support for supporting the front of the load above the chassis is s rigidly mounted to the sub-frame on which it is mounted and the sub-frame is rigidly mounted on the chassis rails. This pivoting action is quite different to that which takes place when the barrel is physically pivoted to discharge material from the barrel. 10 Further, it should be appreciated that the barrel support posts are held in their desired, or preferred, position by their attachment to the barrel support formation and the engagement of these members of the support frame with the barrel. As such, the pivotal mountings do not require any resilient biasing means, e.g. in the form of a torsion spring, to bias the posts towards a preferred 15 position. BRIEF DESCRIPTION OF THE DRAWINGS A vehicle that is a concrete transport truck in accordance with this invention 20 may manifest itself in a variety of forms. It will be convenient to hereinafter provide a detailed description of one or more embodiments of the invention with reference to the accompanying drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the invention how to put the invention into practice. It is to be clearly 25 understood, however, that the specific nature of this detailed description does not supersede the generality of the preceding statements. In the drawings: Fig. 1 is a three dimensional view of a concrete transport truck as known in the prior art; 30 Fig. 2 is a three dimensional view of the truck of Fig 1 with parts removed to show different types of flexing of the chassis during use of the truck. All can occur simultaneously; 20 Fig 3 is a rear view of the truck of Fig 1 while travelling on an uneven road surface; 5 Fig 4 is a side view of part of the truck of Fig 3 again showing the truck travelling along an uneven road surface; Fig 5 is a side view with some details omitted of a vehicle in accordance with one embodiment of the invention; 10 Fig 6 is a three dimensional view of a support mounted on the chassis of the vehicle of Fig 5 with a barrel on the support shown in phantom lines; Fig 7 is an enlarged three dimensional view of the support of Fig 6; 15 Fig 8 is a part sectional rear end view of an upper region of the support and barrel of Fig 6 showing the track ring of the barrel being supported by the trunnion and also showing a transverse roller bearing against a rear surface of the track ring; 20 Fig 9 is a rear view of a lower region of the support showing in particular the mounting of the support on the chassis; Fig 10 is a side view of the lower region of the support shown in Fig 9; 25 Fig 11 is a schematic top plan view of the support of Fig 7 mounted on the chassis which is shown in phantom lines; and Fig 12 is a schematic side view of the support frame assembly of Fig 7 30 mounted on the chassis, again with the chassis shown in phantom lines. Figs 1 to 4 illustrate a concrete transport truck that is known in the art. In the drawings the truck is indicated generally by the reference numeral 1.

21 The truck, which has only been shown very schematically, has some fairly standard features. For example, the truck has a driver's cabin towards its front and a drive unit in the form of a truck engine, e.g. a diesel engine, located s underneath the cabin, or in front of the cabin. The truck also includes a set of front wheels near the front and then a set of rear wheels towards its rear. Typically, the set of rear wheels has four wheels on each side of the vehicle. This is made up of two pairs of wheels. One pair of wheels is forward of a support point for the rear wheels and the other pair of wheels is rearward of the 10 support point. Thus, the set of rear wheels comprise four wheels on each side of the chassis. The truck further includes a suspension for damping bumps as the truck travels along the road. In the example truck shown in the drawings, the suspension is 15 an air bag suspension that provides a softer ride for the driver. However, with the softer air bag suspension, the chassis and therefore also the sub-frame, is subjected to a greater level of flexing during use than if a rubber suspension is used. 20 Generally, a company wanting a concrete transport truck purchases a basic truck from a range of commercially available trucks. This truck is in a basic form with a cabin, an engine and a pair of chassis rails extending rearward from the cabin. The customer chooses the features that they want and these are then installed on the truck that they have purchased. Often, companies choose 25 a truck that has air bag suspension. The company then engages an engineering company to design and build the concrete mixer and support and mount it on the chassis of the truck. The engineering company then has to design and build a support and barrel as best they can, based on the truck that they are given to work with by the client. 30 In Figs 5 to 12 a vehicle that is a concrete transport truck, in accordance with this invention, is indicated generally by the reference numeral 10.

22 The truck 10 comprises broadly a chassis 12, a support shown generally by numeral 13 and a barrel 15 supported spaced above the chassis 12 by the support 13. 5 Generally the truck 10 has two sets of wheels. The first set is near a front 14 of the vehicle 10 and the second set comprising four wheels on each side of the vehicle 10 is positioned towards a rear 16 of the vehicle 10. The barrel 15 is oriented on its side and has a drive for driving it to rotate in use. 10 The barrel 15 is supported by a gearbox flange 18 that is bolted to the barrel 15 towards the front of the barrel 15. The gearbox, in turn, is driven by a hydraulic motor 19. Naturally, the output shaft from the gearbox is mounted on a bearing that vertically supports it while at the same time, permitting it to rotate. 15 The barrel 15 has a track ring 20 towards its rear. The track ring 20 extends circumferentially around the outer surface of the barrel 15. The barrel 15 is supported on this track ring towards its rear by means of the support 13. The support 13 permits the barrel 15 to rotate but does not actively drive the barrel 15 to rotate. 20 As shown in Fig 6, the chassis 12 comprises two laterally spaced chassis rails 30 and 32 extending from the cabin of the vehicle 10 to a rear at the rear 16 of the vehicle 10. The chassis 12 also includes cross members (not shown) extending between the two chassis rails 30 and 32 at spaced intervals along the 25 length of the rails 30, 32. The cross members serve to stiffen and strengthen the chassis 12. The chassis rails 30, 32 may have a U-shape in cross section and are usually made out of steel. The chassis rails 30, 32 may also have gussets to further stiffen and strengthen them. 30 As shown in Figs 6 and 7, the support 13 comprises a broadly horizontally extending sub-frame 35 that lies across a rear section of the chassis 12. The sub-frame 35 comprises two laterally spaced support frame rails 37, 38 that each lie on top of a said chassis rail 30, 32. The sub-frame 35 also includes a 23 transverse member 39 extending between the two support frame rails 37, 38. In the drawings, this transverse member 39 is positioned at the rear ends of the support frame rails 37, 38. The sub-frame 35, like the chassis 12, is made out of steel. 5 The support 13 also includes a barrel support frame 80 that extends up from the sub-frame 35 towards the rear thereof. The barrel support frame 80 comprises a pair of laterally spaced support posts 82, 84 extending up from the sub-frame 35. More specifically, the posts 82, 84 extend up from the rear of the sub-frame 10 35, near the rear of the vehicle 16. The posts 82, 84 are laterally spaced apart from each other and in fact, are arranged such that each post 82, 84 is broadly aligned with a rail 37, 38 of the sub-frame 35. The posts 82, 84 are sized to extend from the sub-frame 35 up to the barrel 15 that they are required to support. Further features of the barrel support frame will be described later on in 15 the description. The frame is shown very clearly in Figs 6 and 7. The barrel support frame is pivotally mounted to the sub-frame 35 by means of pivotal mountings 60 on left and right sides of the frames. The pivotal mounting 60 is shown in some detail in Figs 9 and 10. Each pivotal mounting 60 20 comprises a rod or pin 62 and a sleeve 64 that circumferentially surrounds and receives the rod 62 in a way that permits the sleeve 64 to pivot relative to the rod 62. The rod is mounted to the sub-frame and thus, is fast with the sub frame. On the other hand, the sleeve 64 is fast with the barrel support frame and in particular, each sleeve is fixed to a lower end of a said post of the barrel 25 support frame. Thus, by having the rod mounted on the sub-frame and the sleeve on the post, the post can pivot relative to the sub-frame and the chassis. A bearing 65 is sandwiched between the rod 62 and the sleeve 64 to permit the sleeve 64 to be supported on the rod 62 while at the same time permitting the 30 sleeve 64 and post to pivot relative to the rod 62 and sub-frame with low frictional resistance.

24 In the illustrated embodiment the bearing 65 is a spherical bearing. This type of bearing 65 is preferred because it not only permits pivoting about its axis but it also permits rolling from left to right to some extent. This is useful because the chassis can undergo some rolling from left to right due to uneven road surfaces s when driving on the road and this can help accommodate the rolling, bending and twisting and not transfer it through to the sub-frame 35. The pivotal mounting 60 includes two spaced plates 66, 67 effectively forming part of the sub-frame 35 through which the rod 62 passes. The plates are not 10 positively attached to the rod which passes through apertures defined in the plates with a small amount of clearance. The pivotal mounting also includes a locking pin 69 that passes transversely through an inner end portion of the rod 62. This pin helps to hold the rod in position preventing it from being pulled through the holes in the plates. The pin is held in position by means of a 15 retaining bolt and bracket, as shown in Fig 10. The sleeve and bearing are effectively positioned between these two spaced plates. The plates are sized to resist the sleeve being slid off the rod and thus, effectively hold the pivotal mounting in the assembled condition. The pivotal 20 mounting may also include spacers 68 between the end plates 66, 67 and the bearing 65 to pack the bearing tightly in position so that it does not slide about. In the Fig 5 embodiment the sub-frame 35 only extends a short distance forward from the rear of the chassis 12. Specifically, it does not extend the full 25 length of the chassis rails 30, 32. This is what is known as a short chassis sub frame. In this form, the support 13 further includes a further sub-frame 40 towards the front of the chassis 12. This further sub-frame 40 similarly comprises a pair of support rails, one of which is shown and is indicated by numeral 42 mounted on the chassis rails 30, 32 and at least one cross member 30 (not shown) extending between the two support rails 42. Turning back now to describe the more rearward sub-frame 35, each support rail 37, 38 of the sub-frame 35 is mounted to the associated chassis rail 30, 32 25 by means of two longitudinally spaced chassis attachment elements 50, 52. These are shown particularly clearly in Figs 6 and 7. One of the chassis attachment elements 50 is positioned at the rear of the 5 chassis rail 30 or 32 and mounting rail 37 or 38 and can conveniently be called a rear chassis attachment element. Each chassis attachment element comprises a linear member that is sufficiently long to extend across the side of the chassis rail 30 and be fixed thereto and then extend across to the support rail and across the side of the rail 37 and be fixed thereto. 10 The rear chassis attachment element 50 is rigidly fixed and mounted to the chassis rail 30. In the illustrated embodiment, this is accomplished by means of a plurality of bolts that are passed through the chassis attachment element 50 and also the chassis rail 30. This ensures that the chassis attachment element is 50 cannot move, or pivot, relative to the chassis rail 30. The rear chassis attachment element 50 is mounted to the support rail 37 in a different manner that is clearly shown in Fig 9 and will be described below. 20 The rod of the pivotal mounting passes through an aperture in the rail 37 that effectively forms one of the plates of the pivotal mounting, as described above in the description of the pivotal mounting. It is not positively fixed to the rail and can adjust relative to the rail. The rod is, however, positively attached to and fast with the chassis attachment element. 25 Thus, the rod projects out from the chassis attachment element and through apertures in the support rail of the sub-frame. This retains the chassis rail in position on the chassis rail but does not stop the support rail adjusting subtly to the chassis rail. The rod is well and truly captured on the support rail by the 30 locking pin passed through the rod on the other side of the support rail. The other chassis attachment element 52, which is the front chassis attachment element, is positioned towards the front of the support rail 37. The front 26 attachment element 52 is attached to respectively the chassis rail and the support rail by passing a plurality of bolts between the two, as described above for the attachment of the element 50 to the chassis rail 30. This ensures a rigid mounting or fixing of the mounting rail onto the chassis rail. It is almost as if the s support rail is clamped to the chassis rail at two longitudinally spaced positions along its length. Similarly, the further sub-frame 40 towards the front of the chassis rails 30, 32 has only rigid and fixed mountings of chassis attachment elements 70, 72 to 10 each of the chassis rails 30, 32 and the support rails 42. The barrel support frame 80 has been described briefly above and further includes upper and lower cross members 86, 88 extending between the two posts 82, 84 at respectively the top and the bottom of the posts 82, 84. The 15 cross members 86, 88 help to provide the barrel support frame 80 with the necessary strength. In addition, the barrel support frame 80 further includes a barrel support formation for physically supporting the barrel 5. The barrel support formation comprises a pair of laterally spaced trunnion rollers 90, 92 mounted on the upper cross member 86. 20 As shown in Fig 8, the barrel support frame 80 also includes a pair of transverse rollers 95, 96 that are positioned behind the track ring 20 of the barrel 15. These rollers 95, 96 bear up against the rear surface of the track ring 20 and assist in holding the barrel 15 in its correct longitudinal position. The rollers 95, 25 96 resist any rearward displacement of the barrel during driving of the truck on the roads. With the possible additional flexing of this chassis due to the pivotal mounting the rollers 95, 96 provide an additional mechanism for helping to ensure that the 30 barrel stays in its correct position on the truck 10. In use the concrete truck is used to transport batches or loads of concrete from a mixing plant to a building site, where the concrete is to be used.

27 This process is initiated when the barrel of a truck is filled with concrete at the plant. The load would have a volumetric of about 5-8 m 3 and this would translate to a weight of about 5 to 18 ton which is obviously a heavy load for the 5 support to hold above the chassis rails. The truck is then driven on public roads to the site where the material is needed. In the course of travelling on the roads, the truck will be subjected to uneven road surfaces including bumps, humps and the like. When this occurs the chassis rails may want to flex, particularly if the truck is fitted with air bag suspension, as is often the case these days. 10 During the travel along roads particularly where the chassis of the truck is of the air bag type, the chassis undergoes a fair amount of flexing. Generally, the chassis is made of fairly narrow gauge material and can flex a fair amount. The chassis rails 30, 32 may tend to bend down towards their rear ends. This has 15 the affect of moving the rear of the chassis rails, e.g. downwardly due to the flexing of the chassis rails under the weight of the load. When this occurs, the pivotal mounting of the barrel support frame to the sub frame 35 and particularly the support rails permits a certain amount of 20 movement of the barrel support frame relative to the sub-frame 35 and chassis to avoid transmitting the force of this bending through to the sub-frame 35 and barrel support frame. In addition, the spherical bearings 65 can also tilt left or right and this can assist in accommodating stresses caused by twisting of the chassis rails due to unevenness in the rods. 25 Applicant envisages that this invention will yield sub-frames that have a considerably longer life than is currently being experienced with trucks with air suspensions. This will result in lower maintenance costs for the cement mixers. It will also mean that they have less downtime when they are out of service for 30 repairs. In the experimental work done by the Applicant itself, or through its agents, the sub-frame illustrated in the drawings has proved efficacious at accommodating movement in the chassis during travel of the truck. Primarily, this is a bending of 28 the chassis rails in a longitudinal direction as a result of the soft spring of the air suspension and the narrow gauge of the steel of the chassis rails. However, the movement is not limited to bending downwardly towards the rear end. The end may also bend upwardly in response to the truck travelling over a bump in the s road. The movement might also be a twisting of the chassis where the two chassis' rails move differently to each other. With prior art sub-frames where the sub-frame is rigidly mounted on the chassis any yielding of the chassis is immediately transmitted as a force through to the 10 sub-frame, which then acted to resist this yielding of the chassis and hold the assembly stiffly. However, this imposed a strain on the sub-frame leading to fatigue of the steel of the sub-frame often after only a limited amount of usage. The fatigue of the sub-frame can be catastrophic and the exact timing of the failure can be hard to predict. 15 An advantage of a sub-frame and concrete mixer as described above with reference to the drawings is that it is relatively easy to build and does not involve major changes to the overall sub-frame. There are only minimal changes to the front end of the sub-frame. Further, the changes to the rear end 20 of the sub-frame are not complex and do not involve a large number of additional members. A yet further advantage of the invention is that an existing truck with a concrete mixer and sub-frame mounted on it can be modified to incorporate the invention 25 without too much work. The rear bowl supporting members that are rigidly attached to the chassis and extend up to support the bowl will be removed and replaced by the short chassis mounting members, the pivot assembly and the bowl support members. 30 It will of course be realised that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

Claims (20)

1. A transport truck having a rotatable mixer barrel, the truck comprising: a chassis including a pair of laterally spaced chassis rails extending in a s longitudinal direction; a barrel having a front and a rear that rotates about a substantially horizontal axis; a front barrel support mounted on the chassis rails comprising a substantially rigid front barrel support frame that is substantially rigidly mounted 10 on the chassis rails which supports the front of the barrel in a way that enables the barrel to rotate on the front barrel support and enables a barrel drive arrangement to be driveably coupled to the front of the barrel; and a rear barrel support including a rear barrel support frame mounted on the chassis rails and supporting the rear of the barrel spaced above the chassis 15 rails in a way that enables the barrel to rotate, the rear barrel support frame being able to pivot in a longitudinal direction relative to the chassis to adjust for deformation of the chassis rails in a longitudinal direction.

2. A transport truck having a mixer barrel according to claim 1, wherein the 20 rear barrel support frame includes at least one longitudinal support formation that acts against a rearward facing surface of the barrel to retain or stop the barrel in a longitudinal direction.

3. A transport truck having a mixer barrel according to claim 2, wherein the 25 at least one longitudinal support formation comprises at least one roller that is positioned so that it can roll over a rearward facing surface of the barrel.

4. A transport truck having a mixer barrel according to claim 2 or claim 3, wherein the at least one longitudinal support formation comprises two laterally 30 spaced retaining rollers that are positioned to run over a rearward facing surface of the track ring. 30

5. A transport truck having a mixer barrel according to any one of claims 1 to 4, further including a rear sub-frame which is mounted on the chassis rails towards the rear thereof, and wherein each support post is mounted on the rear sub-frame, at or towards its lower end, by means of a pivotal mounting whereby 5 to enable the rear barrel support frame to pivot in a longitudinal direction.

6. A transport truck having a mixer barrel according to claim 5, wherein the rear barrel support frame comprises two upright support posts that project up from the rear sub-frame on which the barrel is supported, and at least one cross 10 member extending between the support posts.

7. A transport truck having a mixer barrel according to claim 6, wherein the rear barrel support frame includes an upper cross member towards upper ends of the support posts and a lower cross member towards lower ends of the 15 support post.

8. A transport truck having a mixer barrel according to any one of claims 5 to 7, wherein the pivotal mounting includes a bearing. 20

9. A transport truck having a mixer barrel according to claim 8, wherein the bearing is a spherical bearing that can rock from one side to another as well as pivot forward and rearward.

10. A transport truck having a mixer barrel according to any one of claims 5 25 to 9, wherein the rear barrel support further includes at least one vertical support formation mounted on top of the rear barrel support frame, which supports the rear end of the barrel and over which the barrel rotates.

11. A transport truck having a mixer barrel according to claim 10, wherein the 30 barrel includes a track ring extending circumferentially around the barrel, and the vertical support formation includes two laterally spaced rollers over which the track ring runs. 31

12. A transport truck having a mixer barrel according to claim 7, wherein the front barrel support includes a front sub-frame mounted on the chassis rails towards the front thereof, and the front support frame is substantially rigidly mounted thereon. 5

13. A transport truck having a mixer barrel according to claim 12, wherein the front sub-frame and/or the rear sub-frame includes two longitudinal sub-frame rails which are mounted to the left and right chassis rails respectively. 10

14. A transport truck having a mixer barrel according to claim 13, wherein the two longitudinal sub-frame rails are mounted directly on top of the left and right chassis rails and are fixed to the chassis rails by means of vertically extending chassis attachment elements that extend across the associated sub-frame rail and the chassis rail. 15

15. A transport truck having a mixer barrel according to claim 13 or claim 14, wherein the front sub-frame and/or the rear sub-frame further includes at least one cross frame extending between the longitudinal sub-frame rails. 20

16. A vehicle comprising: a chassis including a pair of laterally spaced chassis rails extending in a longitudinal direction; a load having a front and a rear; a front load support mounted on the chassis rails comprising a 25 substantially rigid front load support frame that is substantially rigidly mounted on the chassis rails which supports the front of the load; and a rear load support including a rear load support frame mounted on the chassis rails and supporting the rear of the load spaced above the chassis rails, the rear load support frame being able to pivot in a longitudinal direction relative 30 to the chassis to adjust for deformation of the chassis rails in a longitudinal direction. 32

17. A transport truck having a mixer barrel that rotates about a broadly horizontal axis, the truck comprising: a chassis including a pair of laterally spaced chassis rails extending in a longitudinal direction; 5 a barrel having a front and a rear that rotates about a substantially horizontal axis; a front barrel support mounted on the chassis rails comprising a substantially rigid front barrel support frame that is substantially rigidly mounted on the chassis rails which supports the front of the barrel in a way that permits it 10 to rotate on the front barrel support and also permits a barrel drive arrangement to be driveably coupled to the barrel; and a rear barrel support mounted on the chassis rails, the rear barrel support including a rear barrel support frame comprises two upright support posts extending up from the chassis rails and at least one cross member 15 extending between the upright support posts towards their upper ends, the rear barrel support frame supporting the barrel in a way that enables the barrel to rotate, and the rear barrel support including a pivotal mounting including a universal bearing that can rock from one side to another as well as pivot forward and rearward, that enables the rear barrel support frame to be able to pivot in a 20 longitudinal direction relative to the chassis to adjust for deformation of the chassis rails in a longitudinal direction.

18. A transport truck having a mixer barrel according to claim 17, wherein the rear barrel support frame includes at least one longitudinal support formation 25 which act against a rearward facing surface of the barrel to retain or stop the barrel in a longitudinal direction.

19. A transport truck having a mixer barrel according to claim 18, wherein the at least one longitudinal support formation comprises at least one roller that is 30 positioned such that it can run over a rearward facing surface of the barrel. 33

20. A transport truck having a mixer barrel substantially in accordance with the detailed description on pages 17 to 23 of the specification and as illustrated in Figures 4 to 12 of the drawings.