The present invention relates to a belt conveyor of the type in which a continuous belt runs along a support duct where the support duct is carried on an undercarriage for raising and lowering movements of a discharge end of the duct and where an input drive member for driving the belt is mounted at or on the undercarriage.
Belt conveyors are well known in which the belt passes through a duct which is usually a cylindrical tube so that the belt is curved as it sits against the lower part of the tube while sliding along the tube. The return run of the belt passes on the outside of the tube and is sometimes, but not always, contained in a housing attached to the lower part of the tube and extending downwardly and outwardly therefrom. At a top end, the belt passes around an idler roller so as to discharge material at the roller where the belt turns to move along the return run. At the lower end there is provided a hopper into which material is fed so as to fall onto the belt in the hopper with the belt being guided around a lower idler roller.
Generally the belt is driven by a drive roller located at a point along its length at the return run so that the belt wraps around the drive roller as well as around one or more idler rollers to guide the belt in its movement around the drive roller.
The drive roller is located on the underside of the tube at the optional cover. The drive roller is driven generally by a belt which runs from a drive system to the drive roller.
The tube carrying the belt is supported on an undercarriage which includes a transverse axle by which the conveyor can be rolled from place to place. A first leg assembly extends from the axle upwardly and this is extendable or moveable so as to raise and lower the upper end of the tube to change the height of the discharge onto the belt. A second leg assembly extends from the axle to the tube at a position adjacent the lower end and the second leg assembly can pivot relative to the tube as the first leg assembly is operated to effect the raising and lowering movement.
The simplest undercarriage includes simply two such legs together with a single axle. However more complex undercarriages can be provided.
Generally the belt driving the drive roller passes from an input drive system on the undercarriage generally adjacent the axle. The input drive member can comprise simply a PTO input coupling for receiving drive from a tractor. However the system can include a motor so as to avoid the necessity for connection to a drive output of a tractor. The motor can be electric or an internal combustion engine or can be any other suitable source of power.
This arrangement has been utilised for many years but the drive belt to the drive roller from the power input is a source of problem in that it requires adjustment and replacement when worn.
It is an object of the invention to provide an improved belt conveyor and particularly in which the drive system to connect an input drive to the belt is improved.
According to one aspect of the invention there is provided a belt conveyor comprising:
a continuous belt having a material transportation run and a return run such that movement of the belt along its length causes the belt to move continuously through the transportation run and the return run;
a duct for supporting the transportation run of the belt, the duct having a feed end at which material to be transported is deposited onto the transportation run of the belt for movement along the belt and a discharge end at which the material transported by the belt is discharged from the belt;
the return run of the belt being guided along an underside of the duct;
an undercarriage for supporting the duct and arranged to cause raising and lowering movement of at least the discharge end of the duct;
a drive roller in contact with the belt for driving the belt along its length;
an input drive member for supplying a drive force for drivingly rotating the drive roller;
the input drive member and the drive roller being mounted on the undercarriage at respective positions thereon which remain substantially stationary as the duct is moved in said raising and lowering movement so that the input drive member remains in a fixed position as the duct is moved in said movement and so that the drive roller is fixed relative to the input drive member to receive drive therefrom without necessity for adjustment as the duct is moved;
the drive roller being spaced from the return run of the belt on the underside of the duct and the belt including a divergent portion having two runs extending from the return run to and from the drive roller to receive drive therefrom;
the undercarriage and the position of the drive roller thereon being arranged such that the length of the divergent portion remains constant as the duct is moved in said movement.
Preferably the undercarriage includes a first leg assembly which is of constant length and at a fixed position on the duct and a second leg assembly which is adjustable to cause said movement of the duct, the divergent portion of the belt extending along the first leg assembly from a guide system at an end thereof adjacent the duct to the drive roller adjacent an opposed end of the first leg assembly.
Preferably the drive roller is carried on a mounting assembly at the opposed end of the first leg assembly.
Preferably undercarriage includes an axle having ground wheels thereon the first and second leg assemblies converge to said axle.
Preferably there is provided at least one idler roller at the drive roller around which the belt passes so as to wrap the belt around the drive roller, the idler roller being adjustable in position relative to the drive roller to effect tensioning of the belt.
Preferably there are at least three idler rollers arranged to guide the belt from a first contact point on the drive roller partly around the drive roller and back to the same side of the drive roller as the first contact point.
Preferably the divergent portion is arranged on the return run at a position spaced from one end so as to define a first portion of the return run and a second portion of the return run, wherein the first leg assembly is pivotal relative to the duct about a horizontal axis at the duct transverse to the duct and wherein the divergent portion is guided at the duct by a first idler roller around which the first portion of the return run is wrapped and two second rollers which guide opposite sides of the second portion to maintain the two runs of the divergent portion spaced and substantially parallel.
Preferably the two runs of the divergent portion are contained within a cover assembly along the first leg assembly.
Preferably the input drive member comprises a PTO coupling for attachment to a PTO shaft of a drive tractor and wherein the PTO coupling is directly attached to the drive roller such that the PTO coupling is maintained at a fixed position relative to the ground as the duct is moved in said movement.
Preferably the input drive member a drive motor which has an output shaft directly connected to the drive roller without intervening drive belts.
Preferably the duct comprises a tube.
According to a second aspect of the invention there is provided a belt conveyor comprising:
a continuous belt having a material transportation run and a return run such that movement of the belt along its length causes the belt to move continuously through the transportation run and the return run;
a duct for supporting the transportation run of the belt, the duct having a feed end at which material to be transported is deposited onto the transportation run of the belt for movement along the belt and a discharge end at which the material transported by the belt is discharged from the belt;
the return run of the belt being guided along an underside of the duct;
an undercarriage for supporting the duct including:
a base assembly with ground wheels for movement of the undercarriage across the ground,
a first leg assembly having one end pivotally connected to the base assembly and extending therefrom to the duct at a position adjacent to the feed end, the first leg assembly being of constant length, arranged at a fixed position on the duct and pivotally connected to the duct for pivotal movement about a horizontal axis transverse to the duct,
and a second leg assembly extending from the base assembly to the duct adjacent to the discharge end and to arranged to cause raising and lowering movement of the discharge end of the duct;
a drive roller in contact with the belt for driving the belt along its length;
an input drive member for supplying a drive force for drivingly rotating the drive roller, the input drive member and the drive roller being mounted on the undercarriage at said one end of the first leg assembly;
the belt including a divergent portion having two runs extending from the return run to and from the drive roller to receive drive therefrom, the divergent portion being guided to run along the first leg assembly from the end thereof at the duct to the drive roller at said one end thereof.
According to a third aspect of the invention there is provided a belt conveyor comprising:
a continuous belt having a material transportation run and a return run such that movement of the belt along its length causes the belt to move continuously through the transportation run and the return run;
a duct for supporting the transportation run of the belt, the duct having a feed end at which material to be transported is deposited onto the transportation run of the belt for movement along the belt and a discharge end at which the material transported by the belt is discharged from the belt;
the return run of the belt being guided along an underside of the duct;
an undercarriage for supporting the duct and arranged to cause raising and lowering movement of at least the discharge end of the duct;
a drive roller in contact with the belt for driving the belt along its length;
an input drive member for supplying a drive force for drivingly rotating the drive roller;
at least one idler roller at the drive roller around which the belt passes so as to wrap the belt around the drive roller, the idler roller being adjustable in position relative to the drive roller to effect tensioning of the belt;
wherein the position of the idler roller is adjusted by a hydraulic cylinder and wherein the hydraulic cylinder is attached to an accumulator of hydraulic fluid arranged to receive a fluid at a predetermined pressure such that the idler roller is pulled in a direction to apply tension to the belt at a predetermined force thus maintaining a predetermined tension in the belt while accommodating changes in belt length.
Preferably there are at least three idler rollers arranged to guide the belt from a first contact point on the drive roller partly around the drive roller and back to the same side of the drive roller as the first contact point.