AU4413593A - Lifter arm - Google Patents

Description

LIFTER ARM TECHNICAL FIELD This invention relates to a lifter arm and has been devised particularly though not solely for lifting refuse or recycling bins from a ground level position and up¬ ending those bins into a collection vehicle to which the arm is attached.

BACKGROUND ART In the past apparatus has been provided in the form of a lifter arm to enable the mechanical lifting and emptying of a refuse or recycling container, typically a large eg: 240 litre wheeled bin from a ground level position into the hopper or chute of a collection vehicle. In the so-called "side lifter" configuration, the arm is provided on the side of a truck, on a sliding base which can be extended from the side of the truck until the end of the arm engages with the container which is then lifted and up-ended into the body of the truck by the lifter arm. The arms are typically comprised of an articulated mechanical linkage operated by appropriate hydraulic piston and cylinder assemblies.

Lifter arms of this type previously known have the disadvantage that the initial and final movement of the container, ie : at the point of lifting from the ground, and at the point of discharging into the vehicle, is too rapid which can cause problems and more importantly can cause impact between the container and the vehicle with resultant damage to either or both. It is desirable to provide a lifter arm mechanism which will enable a relatively soft or slow pick-up and similarly a soft or slow delivery into the receiving vehicle. To achieve this aim in an efficient cycle time, the arm movement at the beginning and end of the lifting stroke must be comparatively slow to the lifting speed through the middle of the stroke.

DISCLOSURE OF THE INVENTION The present invention therefore provides a mechanical lifter arm particularly adapted for lifting and up-ending a bin for emptying into a collection vehicle, said lifter arm -comprising a primary arm pivotally mounted to a main frame, a secondary arm pivotally mounted to the end of the primary arm, a primary four bar linkage operable by an hydraulic piston and cylinder assembly on the inner part of the primary arm, and a secondary four bar linkage on the outer part of the primary arm, between the primary arm and the secondary arm, all pivot points for the arms and linkages having parallel axes and typically lying in substantially horizontal planes.

Preferably the primary four bar linkage when viewed in elevation has two upper pivot points fixed relative to the main frame, one of those pivot points comprising the pivot for the primary arm, and wherein the hydraulic piston and cylinder assembly is operable between a further pivot point on the main frame and the pivot point of the primary four bar linkage diametrically opposite to the pivot for the primary arm. Preferably the secondary four bar linkage comprises a common link with the primary four bar linkage, a continuation of the primary arm, a portion of the secondary arm, and a further link between the secondary arm and the pivot point on the common member which is remote from the primary arm.

Preferably the said pivot point on the common member remote from the primary arm is also the point of connection of the hydraulic piston and cylinder assembly to the lifter arm mechanism. Preferably the further link between the secondary arm and the common link is adjustable for length.

Preferably the secondary arm is provided with engagement means for lifting a refuse or recycling bin.

Preferably the main frame is attached to the collection vehicle by way of a telescopic arm mechanism permitting horizontal movement of the main frame away from and toward the collection vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS Notwithstanding any other forms that may fall within its scope, one preferred form of the invention will now be described by way of example only with reference to the accompanying drawings, in which: - Fig. 1 is a perspective view of a lifter arm mechanism according to the invention, extended from the side of a collection vehicle in the lowered position engaged with a bin at ground level;

Fig. 2 is a similar view to Fig. 1 showing the lifter arm mechanism retracted toward the collection vehicle and in the raised position with the bin up-ended over a collection hopper;

Fig. 3 is a side elevation of the lifter arm according to the invention; Fig. 4 is an end elevation of the lifter arm shown in Fig. 3 with the arm in the lowered position;

Fig. 5 is a view similar to Fig. 4 with the arm in an intermediate position;

Fig. 6 is a view similar to Fig. 4 with the arm in the fully raised position; and

Fig. 7 is a diagrammatic view of the lifter arm geometry showing the sequence of linkage movement between the lowered and raised positions.

MODES FOR CARRYING OUT THE INVENTION In the preferred form of the invention the lifter arm is mounted on a truck (1) by way of a telescopic arm

(2) protruding from the side of the truck and movable between a position away from the truck as shown in Fig. 1 to a position close coupled to the truck as shown in Fig. 2.

The lifter arm is mounted on the end of the telescopic arm (2) and comprises a main frame (3) to which is pivotally mounted a primary arm (4) and a secondary arm (5) articulated to the end of the primary arm (4) .

The lifter arm is actuated by a hydraulic piston and cylinder assembly (6) .

The lifter arm is operable to engage a refuse or recycling bin (7) and to lift the bin from a ground level

(eg: kerbside) position as shown in Fig. 1 to a raised position as shown in Fig. 2 where the bin is up-ended for emptying into a collection chute (8) of the collection vehicle.

The construction of the mechanism will be specifically described with clear reference to Figs. 4, 5 and 6.

The primary arm (4) is pivotally connected to the main frame (3) by way of a pivot pin (9) at the end of a cantilevered arm (10) which forms a rigid extension of the main frame (3) . The primary arm (4) is rotated about the pivot (9) by way of a primary four bar linkage (11) which comprises the cantilever arm (10) , a portion of the primary arm between pivot (9) and a further pivot pin (12), a primary toggle link (13) pivotally mounted to the main frame about pivot point (14) and a common toggle link (15) pivotally connected by way of pivot pin (16) between primary arm (4) and primary toggle link (13) . The primary four bar linkage (11) is operable by a piston and cylinder assembly (6) shown diagrammatically in Figs. 4, 5 and 6 by a long chain line between pivot points (16) and a base mount pivot (17) on the lower portion of the main frame (3) . The lifter arm further comprises a secondary arm (5) pivotally mounted to the end of the primary arm (4) by way of pivot pin (18) and rotatable relative to the primary arm by a secondary four bar linkage (19) which comprises the portion of the primary arm between pivots (12) and (18) , the common toggle link (15) located between pivot pins (12) and (16) , a portion of the secondary arm between pivot pin (18) and a further pivot pin (20) and an adjustable link (21) extending between pivot pins (16) and (20) . The secondary arm extends downwardly from the pivot pins (18) and (20) to include a fork or hook portion (22) which is engageable under the rim of the container (7) and further means, eg: suction caps (23) for engaging the side of the bin (7) with the secondary arm (5) .

As can be seen with sequential reference to Figs. 4, 5 and 6, as the hydraulic piston and cylinder assembly is extended, pushing the pivot point (16) upwardly and outwardly away from the main frame (3) , the primary arm is caused to rotate about pivot pin (9) and the secondary arm to articulate about pivot pin (18) at the end of the primary arm.

Due to the geometry of the two four bar linkages, the ensuing movement is relatively slow at the commencement of movement, ie : from the position shown in Fig. 4, relatively fast through the intermediate stages of lifting the bin, and relatively slow or soft in the final stages of movement approaching the position shown in Fig. 6. In this manner it is possible to provide a mechanical lifting arm which is quick and therefore efficient in operation but yet which has a gentle pick-up and set-down, and most importantly a gentle or slow approach speed of the bin to the collection vehicle, minimising damage from impact between the bin and the vehicle .

The specific geometry of the linkage movement is most clearly seen in Fig. 7, and although variations will perform according to the invention, it has been found that the mechanism works effectively with the following ratios of link lengths.

Link between pivot pins : Length (mm)

9-14 112

9-12 96 12-16 125

14-16 185

9-18 570

18-20 126

16-20 480 14-16 185

12-18 497

12-16 125 It has also been found that the primary arm (4) should be formed to a cranked configuration as shown, subtending an angle of 37° between pivot points (18) (9) and (12) . The hydraulic piston and cylinder assembly typically has a stroke length of 430 mm. All of the distances given above are typically in millimetres but it will be appreciated that the mechanism can be scaled up or down to any desirable size. The length of the adjustable link (21) , ie: the length between pivot pins (16) and (20) can be adjusted to alter the final position of the bin in the raised position as shown in Fig. 6 relative to the hopper in the collection vehicle.

Claims (9)

CLAIMS :

1. A mechanical lifter arm particularly adapted for lifting and up-ending a bin for emptying into a collection vehicle, said lifter arm comprising a primary arm pivotally mounted to a main frame, a secondary arm pivotally mounted to the end of the primary arm, a primary four bar linkage operable by an hydraulic piston and cylinder assembly on the inner part of the primary arm, and a secondary four bar linkage on the outer part of' the primary arm, between the primary arm and the secondary arm, all pivot points for the arms and linkages having parallel axes and typically lying in substantially horizontal planes.

2. A lifter arm as claimed in claim 1 wherein the primary four bar linkage when viewed in elevation has two upper pivot points fixed relative to the main frame, one of those pivot points comprising the pivot for the primary arm, and wherein the hydraulic piston and cylinder assembly is operable between a further pivot point on the main frame and the pivot point of the primary four bar linkage diametrically opposite to the pivot for the primary arm.

3. A lifter arm as claimed in either claim 1 or claim 2 wherein the secondary four bar linkage comprises a common link with the primary four bar linkage, a continuation of the primary arm, a portion of the secondary arm, and a further link between the secondary arm and the pivot point on the common member which is remote from the primary arm.

4. A lifter arm as claimed in claim 3 wherein the said pivot point on the common member remote from the primary arm is also the point of connection of the hydraulic piston and cylinder assembly to the lifter arm mechanism.

5. A lifter arm as claimed in claim 3 wherein the further link between the secondary arm and the common link is adjustable for length.

6. A lifter arm as claimed in any one of the preceding claims wherein the secondary arm is provided with engagement means for lifting a refuse or recycling bin.

7. A lifter arm as claimed in any one of the preceding claims wherein the main frame is attached to the collection vehicle by way of a telescopic arm mechanism permitting horizontal movement of the main frame away from and toward the collection vehicle.

8. A lifter arm as claimed in any one of the preceding claims wherein the primary four bar linkage comprises; a cantilevered arm forming a rigid extension of the main frame and having a length between pivot points of 112 mm, a portion of the primary arm having a length between pivot points of 96 mm, a primary toggle link pivotally mounted to the main frame and having a length between pivot points of 185 mm, and a common toggle link pivotally connected between the primary toggle link and the primary arm and having a length between pivot points of 125 mm, or larger or smaller variations of the primary four bar linkage where all lengths are increased or decreased in proportion.

9. A lifter arm as claimed in claim 8 wherein the secondary four bar linkage comprises; the said common toggle link having a length between pivot points of 125 mm, a further portion of the primary arm having a length between pivot points of 497 mm, a portion of the secondary arm having a length between pivot points of 126 mm, and an adjustable link extending between the secondary arm and the common toggle link and having a length of approximately 480 mm, or larger or smaller variations of the secondary four bar linkage where all lengths are increased or decreased in proportion.