DE20308046U1 - Rotary mower with quick change device for blades has leaf spring holding blade on retaining bolt and hooked attachment for extra security protruding transversely to axis of bolt opposite cylindrical collar - Google Patents

Abstract

For each blade in the rotary body there is a retaining bolt (H) which has a cylindrical collar (7) as the bearing point for the blade (K) and a leaf spring (B) holding the blade on the bolt. Additional security for the blade is formed by a hooked attachment (9) which protrudes transversely to the axis (X) of the bolt opposite the cylindrical collar. The hooked attachment forms underneath the collar the end of the bolt remote from the rotary body (R ).

Description

GRUNECKER KINKELDEY STOCK'MAtR & .SCH WA NJd AtJJS E R

LAW FIRM

GKS & S MAXIMIUANSTRASSE 58 D-80538 MUNICH GERMANY

Applicant:

FELLA-WERKE GMBH & CO. KG

FELLASTRASSE 2

90537 FEUCHT NEAR NUERNBERG LAWYERS
LAWYERS

MUNICH

DR. HELMUT EICHMANN

GERHARD BARTH

DR. ULRICH BLUMENRÖDER, LLM.

CHRISTA NIKLAS-FALTER

DR. MAXIMILIAN KINKELDEY, LLM.

DR. KARSTEN BRANDT

MICHAEL J. FRANKE, LLM.

UTE STEPHANI

DR. BERND ALLEKOTTE, LL.M.

DR. ELVIRA PFRANG, LLM.

KARIN LOCHNER

BABETT ERTLE

CHRISTINE NEUHIERL

SABINE PRÜCKNER

PATENT ATTORNEYS

EUROPEAN PATENT ATTORNEYS

MUNICH

DR. HERMANN KINKELDEY

PETER H. JAKOB

WOLFHARD MEISTER

HANS HILGERS

DR. HENNING MEYER-PLATH

ANNELIE EHNOLD

THOMAS SCHUSTER

DR. KLARA GOLDBACH

MARTIN AUFENANGER

GOTTFRIED KLITSCH

DR. HEIKE VOGELSANG-WENKE

REINHARD KNAUER

DIETMAR KUHL

DR. FRANZ-JOSEF ZIMMER

BETTINA K. REICHELT

DR. ANTON K. PFAU

DR. UDO WEIGELT

RAINER 8ERTRAM

JENS KOCH, M.S. (U of PA) M.S.

BERND ROTHAEMEL

DR. DANIELA KINKELDEY

THOMAS W. LAUBENTHAL

DR. ANDREAS KAYSER

DR. JENS HAMMER

DR. THOMAS EICKELKAMP

JOCHEN KILCHERT

DR. THOMAS FRIEDE

YOUR REF.

OUR REF.

G 5003-25/Dr

PATENT ATTORNEYS

EUROPEAN PATENT ATTORNEYS

BERLIN

PROF. DR. MANFRED BÖNING

DR. PATRICK ERK, M.S. (MIT)

COLOGNE

DR. MARTIN DROPMANN

CHEMNITZ MANFRED SCHNEIDER

OF COUNSEL PATENT ATTORNEYS

AUGUST GRÜNECKER DR. GUNTER 3EZ0LD DR. WALTER LANGHOFF

DR. WILFRIED STOCKMAIR (-1996)

DATE

22.05.03

Rotary mower and mower blade changing tool

GRÜNECKER KINKELDEY I
STOCKMAIR &
MAXIMILIAN STREET 58
D-80538 MUNICH
GERMANY

+.49 J39 2^3 f O

FAK· * +*49 ^9 2» & 92t93* . . * http://www.grunecker.de e-mail: info@grunecker.de

DEUTSCHE BANK MUNICH No. 17 51734 BLZ 700 700 SWIFT: DEUT DE MM

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Rotary mower and mower blade changing tool

The invention relates to a rotary mower of the design described in the preamble of claim 1 and a mower blade changing tool for a rotary mower according to the preamble of claim 13.

Oscillating mower blades on rotary mowers have to be replaced after a certain period of use due to wear. To increase the service life, it is common practice to design each mower blade with two cutting edges and to use the intact cutting edge when it is worn by turning the mower blade over. The mower blade retaining bolts are usually firmly screwed to the rotary body or mower disc of the mower. The time required to loosen and tighten the retaining bolts to change or turn the mower blade is high.

For this reason, rotary mowers with quick-change devices for mower blades were developed (DE 69 34 709 U or DE 198 56 746 A). In these rotary mowers, the mower blade retaining bolts are attached to a leaf spring arranged beneath the rotary body. The retaining bolt has a free end that can be exposed by elastically deforming the leaf spring, via which the mower blade can be removed and threaded in the blade change position of the leaf spring. To change the mower blade, special change tools (mower blade change wrenches) are used, which are inserted between the rotary body and the leaf spring and manipulated in such a way that the leaf spring deforms sufficiently to create space for the mower blade to be removed or threaded on.

In the rotary mower of DE 69 34 709, the retaining bolt attached to the leaf spring has a thickened head at the free end, which is guided through an opening in the mower blade when changing the mower blade. In the mower blade securing position of the leaf spring, the thickened head is pressed with pre-tension into a suitably shaped recess in the underside of the rotary body. Changing the mower blade is nevertheless associated with considerable effort, because the changing tool is difficult to handle.

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pülieren must be held with at least one hand and at the same time the mowing blade must be moved back and forth until it can be pushed over the thickened head.

In the rotary mower known from DE 198 56 746 A, an insert for the thickened head is attached to the rotary body at the free end of the retaining bolt fixed in the leaf spring. When changing the mowing blade, the changing tool must be held with one hand using relatively high force and then the mowing blade must be moved back and forth until its opening passes over the thickened head. Handling it requires considerable skill.

Rotary mowers are also known in practice in which the retaining bolts are firmly mounted on the underside of the rotary body. Each retaining bolt has a small head at the free end over which the mowing blade is moved. In these rotary mowers, the leaf spring engages with a hole over the head of the retaining bolt in the locking position. As with the rotary mowers of DE 69 34 709 or DE 198 56 746 A, the mowing blade is secured by the leaf spring during operation and when the rotary body is stopped.

All known designs have the disadvantage that the leaf spring can be elastically deformed by the influence of foreign bodies, e.g. stones or accumulations of grass clippings, to such an extent that the mowing blade can no longer be securely positioned because the mowing blade can then automatically slide over the free end of the retaining bolt and get lost.

The invention is based on the object of specifying a rotary mower of the type mentioned at the beginning, in which the mower blade is held securely even when the leaf spring is deformed, and in which the quick-change device for changing the mower blade is easy to use. A secondary aspect of the object is to specify a mower blade changing tool that works together with the changing device of the improved mower for convenient handling, but also enables convenient handling with other rotary mowers.

The stated object is achieved with the features of claim 1 and, with regard to the interchangeable tool, with the features of claim 13.

In the rotary mower, the hook-shaped attachment reliably prevents the mower blade from coming free, even if the leaf spring is deformed by external influences, because it forces a certain kinematics for the mower blade to come free, which the mower blade cannot carry out without external help. Furthermore, the interaction of the cylindrical collar, which already defines a relatively safe bearing point for the mower blade, and the hook-shaped attachment results in additional protection against the mower blade coming free on its own. This means that, because of the hook-shaped attachment, the mower blade does not slide off the cylindrical collar and come free even if the leaf spring is not securing it, but at most remains secured in a slightly inclined position when the rotary mower is stationary. As soon as the rotating body rotates, the mower blade is forced into the correct position on the cylindrical collar by the centrifugal force and by the hook-shaped attachment.

The tool position holding surface, e.g. on the change tool, causes a self-holding effect of the change tool in the blade change position under the pre-tension of the leaf spring, so that the change tool can be released and the mowing blade can be easily removed or threaded on with both hands. The change tool can be brought into the stable change position via a clearly noticeable pressure point and holds this until force is applied again. The person making the change feels when the stable change tool position has been reached and can let go of the change tool. This makes changing the mowing blade easy, even for people with below-average dexterity. There is also the advantage that by clearly feeling the correct change position of the change tool being reached, the manufacturer of the rotary mower and the change tool has already ensured that the leaf spring is then pushed far enough away from the rotating body to enable the mowing blade to be changed quickly and easily, and that the person making the change is relieved of this task.

It is practical if the hook-shaped attachment points at least essentially inwards towards the centre of the rotating body. With this orientation of the attachment, a secure position of the mowing blade is achieved via the centrifugal force when the rotating body is rotating, even when the leaf spring is deformed. The attachment is also most secure with this orientation when the rotating body is stationary.

The hook-shaped projection below the cylindrical collar advantageously forms the end of the retaining bolt facing away from the rotating body. The projection of the retaining bolt over the rotating body is therefore optimally short, so that a relatively small deformation stroke of the leaf spring is sufficient to be able to change the mowing blade easily.

If, in a preferred embodiment, the hook-shaped projection is offset eccentrically in relation to the cylindrical collar and there is a contact surface for the leaf spring between the collar and the projection, against which the leaf spring rests with pre-tension in the locking position, the leaf spring has a defined position in the locking position that is optimal for the pendulum mobility of the mowing blade. Since the hook-shaped projection then lies in the leaf spring or even penetrates it downwards, foreign bodies can hardly become wedged between the retaining bolt and the leaf spring. The crescent-shaped contact surface offers a large, wear-resistant contact area for the leaf spring.

The hook-shaped attachment has a practical, slanting, curved boundary surface and a flat underside. The receding boundary surfaces with the curved curvature allow the mowing blade to be easily removed or attached when handled correctly. The flat underside, which may be flush with the underside of the leaf spring when it is in the secured position, prevents any projections on which the grass clippings could get caught.

The hook-shaped attachment should have a free end that has an arc and slopes back towards the bottom. This makes it easier to thread the mower blade onto and off.

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In a practical embodiment, the upper side of the hook-shaped attachment facing the rotating body has a largely flat surface, for example in the shape of a circular ring segment, from the ends of which rounded flanks extend essentially to the underside of the attachment. The flat surface serves to support the tilted mowing blade. The rounded flanks allow the mowing blade to be easily manipulated when changing it.

The hook-shaped projection should extend beyond the cylindrical collar by approximately 30% of the outer diameter of the cylindrical collar. This relatively small projection ensures that the mowing blade is held securely in place when the leaf spring is deformed. However, the mowing blade can still be easily changed if handled correctly.

The width of the attachment should correspond to the maximum outer diameter of the cylindrical collar, preferably even smaller, in order to obtain a good securing of the mowing blade in the event of a deformed leaf spring.

In a preferred embodiment, the distance between the deformed leaf spring and the rotating body is such that the cutting end of the mowing blade, when resting on the attachment, can be tilted downwards so far that it comes free of the cylindrical collar on one side, but cannot fall off by itself. It is then held by the attachment. The mowing blade can only be removed if it is moved in this position in the direction in which the hook-shaped attachment points.

Furthermore, in a practical embodiment, the distance between the hook-shaped attachment and the rotating body should be large enough that when the leaf spring is in the blade-changing position, the mowing blade rests on the hook-shaped attachment and the rotating body and is free from the cylindrical collar on one side. The interaction between the rotating body and the hook-shaped attachment initially keeps the tilted mowing blade in a safe position. It can be removed with help from others, but cannot fall off on its own.

It is advisable to provide largely flat counter surfaces on the rotating body and/or on the leaf spring in predetermined areas of engagement of a spreading leg of a change tool, which interact with the spreading leg in such a way that it automatically holds a stable position in the correct mower blade change position, so that the person carrying out the change can let go of the change tool and use both hands to manipulate the mower blade. In this case, it is advantageous if the spreading leg also has at least one widened tool position holding surface. When the change tool is moved, it reaches the stable position via a clearly noticeable pressure point, in which on the one hand the leaf spring is pressed far enough away from the rotating body to be able to easily remove the mower blade, and on the other hand both hands can be used to manipulate the mower blade.

The change tool expediently has a two-leg C-shaped bracket, preferably with a tilting handle arranged thereon, the C-legs of which form a gap at least the width of the mowing blade, and the C-leg ends of which form spreading legs which automatically hold the tool in a stable position between the rotating body and the leaf spring in a predetermined mowing blade change position of the tool. The tilting handle can be made of round material and form a round widening of the holding surface which makes it easier to tilt the spreading leg.

Embodiments of the subject matter of the invention are explained with reference to the drawings. They show:

Fig. 1 is a vertical section of a part of a rotary mower, in an operating position,

Fig. 2 is a similar sectional view representative of an intermediate step in a mower blade change and of a situation where a foreign object is jammed,

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Fig. 3 is a similar sectional view of the final phase of a mower blade change, Fig. 4 and 5 are two perspective views of a retaining bolt, and Fig. 6 is a perspective view of a mower blade changing tool.

A rotary mower M in Fig. 1 to 3 has a rotary body R which can be rotated about a center (not shown) and has at least one mower blade retaining bolt H fixed therein, a mower blade K which is mounted in a pendulum manner on the retaining bolt H and a leaf spring B which is positioned below the rotary body R to secure the mower blade K in the securing position a shown in Fig. 1.

Essential components of the rotary mower M are explained in Fig. 1, while important dimensions and dimensional relationships are explained in Fig. 2 and 3.

The rotary body R in Fig. 1 has a cutout 1 on the edge, below which an insert part 2 is fixed, which contains a through opening 3 (square bore) for a shaft 5 of the retaining bolt H. The shaft 5 has an external thread onto which a retaining nut 4 is screwed, and is secured against rotation by a square 6 in the through opening 3, wherein the locking nut 4 clamps a shoulder of a cylindrical collar 7 adjacent to the square 6 against the underside of the insert part 2. The cylindrical collar 7 has a cylindrical peripheral surface 8, which in the embodiment shown is, for example, concentric with the axis of the shaft 5. The lower, free end of the retaining bolt H is formed by a hook-shaped projection 9, which in the embodiment shown extends essentially in the direction of the center of the rotary body R and protrudes on one side beyond the cylindrical collar 7.

The mowing blade K has a band-like blade body 10 with a cutting end 11 (preferably with two opposing cutting edges) and a holding end 12 in which a through opening 13, e.g. a bore, is provided. With the through opening 13, the mowing blade K sits in a loose sliding fit on the peripheral surface 8

of the cylindrical collar 7. The height of the collar 7 is slightly greater than the thickness of the holding end 12 of the mowing blade K.

The hook-shaped projection 9 is offset off-center with respect to the cylindrical collar 7, so that a contact surface 16 is present between the cylindrical collar 7 and the hook-shaped projection 9. The leaf spring B has an edge region 14 with a through opening 15 (e.g. an elongated hole), which can be larger than the contour of the hook-shaped projection 9. The hook-shaped projection 9 has a height above the contact surface 16 which, in the embodiment shown, is greater than the thickness of the leaf spring B. In the securing position a, the leaf spring B rests against the contact surface 16 with significant pre-tension, with the hook-shaped projection 9 being secured in the through opening 15 or even protruding slightly downwards.

With regard to Fig. 2, it is first assumed that a mower blade change (or turning of the mower blade) is desired. An expansion leg S of a change tool W (Fig. 6 shows a possible embodiment of such a change tool) is initially inserted flat between the rotating body R and the leaf spring B and then tilted by approx. 90°, whereby counter surfaces 18, 19 on the leaf spring B and on the rotating body R possibly interact with largely flat change tool position holding surfaces 17 on the edges of the expansion leg S in such a way that the change tool W is automatically held in a stable position and does not need to be held by hand. Reaching this position is indicated by a clearly noticeable pressure point that must be overcome.

In this blade change position b of the expansion leg S, there is a distance c between the rotation body R and the leaf spring B ₁ , which has been elastically deformed from the securing position a of Fig. 1 into the blade change position f in Fig. 2. Furthermore, a distance d is provided between the hook-shaped projection 9 and the underside of the insert part 2. The holding end 12 of the mowing blade K has a thickness e. The height of the cylindrical collar 7 is slightly smaller than the distance d. By pressing in the direction of an arrow 20 on the cutting end 11 of the mowing blade K, the latter is brought into the tilted position shown in Fig. 2, in which the holding end 12 is on the one hand on the insert part 2 and on the other hand in the area of the edge of the through-opening 13 on the ha-

ken-shaped projection 3. The distance d is dimensioned in relation to the thickness e such that the through opening 13 on the edge area of the cylindrical collar 7 facing away from the hook-shaped projection 9 is free of the latter. The mowing blade K then only needs to be moved in the direction of the arrow 21 until the through opening 13 slides downwards over the hook-shaped projection 9 and comes into the position shown in Fig.

In Fig. 3, the mowing blade K is completely free from the retaining bolt H. It can be easily pulled out in the direction of arrow 22 and turned by 180° or replaced by another identical or similar mowing blade.

Fig. 3 also illustrates the projection g of the hook-shaped extension 9 over the cylindrical collar 7. This projection g amounts, for example, to approximately 30% of the outer diameter h of the cylindrical collar 7.

To insert the mowing blade K, the procedure is reversed, i.e. the mowing blade K is first pushed in with the leaf spring B spread out until it lies with the through opening 13 below the hook-shaped projection 9, similar to Fig. 3. It is then lifted or tilted in the direction of arrow 20 (Fig. 2) until the inside area of the through opening 13 has stepped over the hook-shaped projection 9. The mowing blade K is then pulled outwards until it reaches the position shown in Fig. 2. Finally, the mowing blade K is either lifted or the spreading leg S is tilted back so that the leaf spring B brings the mowing blade K into the operating position shown in Fig. 1. The leaf spring B then rests against the contact surface 16 with pre-tension. To widen the holding surface 17 (more stable position), the spreading leg S has a round profile 33' attached to it, which can be part of a tilting handle 33 (see Fig. 6). Thanks to its roundness, the round profile 33" also makes it easier to tilt the spreading leg S into and out of the stable spreading position.

Next, assume that in Fig. 2 a foreign body (for example with the size of the spreading leg S) is clamped between the rotating body R and the leaf spring B, which presses the leaf spring into the blade changing position f shown in Fig. 2. If necessary, the mowing blade K then tilts with its cutting end 11 in the direction of

·

·

direction of the arrow 20 downwards until its holding end 12 rests on the underside of the insert part and the edge area of the through opening 13 rests on the hook-shaped projection 9. Although the opposite edge area of the through opening 13 has then possibly become free from the cylindrical collar 7, the mowing blade K is nevertheless in a secure position because it cannot fall off the holding bolt H on its own. As soon as the rotating body rotates, the mowing blade is brought back into the operating position shown in Fig. 1 on the cylindrical collar 7 under the centrifugal force and with the help of the hook-shaped projection 9.

Fig. 4 and 5 illustrate a possible embodiment of the retaining bolt H with its shaft 5, the square 6, the cylindrical collar 7 and the hook-shaped projection 9. Thanks to the off-center position of the hook-shaped projection 9, the contact surface 16 has the shape of a crescent moon in order to create a large contact area for the leaf spring B. From the contact surface 16, inclined or rounded transition surfaces 24 run in the direction of the axis X of the shaft 5 to a substantially flat underside 23 of the hook-shaped extension 9. These transition surfaces 24 can run with an arc curvature 25 around the axis X, preferably with a slightly smaller arc curvature than the circular arc of the peripheral surface 8 of the cylindrical collar 7. The hook-shaped extension 9 has a free end 26 protruding beyond the peripheral surface 8, which also runs with an arc curvature 27 and is bevelled in the direction of the axis X and the underside 23. According to Fig. 5, a support surface 29 is defined on the upper side of the hook-shaped extension 9, which can have the shape of a largely flat circular ring segment and is guided to the underside 23 via rounded shoulders 30. The transition from the upper side of the hook-shaped extension 9 to the cylindrical collar is rounded. The width of the hook-shaped projection 9, indicated by k, is at most approximately as large as the outer diameter of the cylindrical collar 7, preferably slightly smaller. The outline of the hook-shaped projection 9, seen in the direction of the axis X, corresponds approximately to the contour of the through-opening 15 in the bed spring B, which is designed as an elongated hole.

Fig. 6 illustrates a mower blade changing tool W which is adapted to the mower blade quick-change device V of the rotary mower M of Fig. 1 to 3, but can also be used for other rotary mowers.

The tool W has a C-shaped bracket 31, the ends of the C-legs of which delimit a gap 32 that is at least as wide as the mowing blade and/or the insert part 2. These C-leg ends form two spreading legs S, one of which is shown in Fig. 2 and 3. The essentially flat change tool position holding surfaces 17 can be clearly seen. A tilting handle 33, e.g. made of round material, extending up to the spreading legs S can be formed on the C-bracket 31, by means of which the tool W can be tilted by approximately 90° in the direction of an arrow 34 between the insertion position i and the blade change position b, whereby the tool automatically holds the position stable in position b and can be released. The change tool W could also be designed with only one spreading leg S, i.e. only have half the C-bracket 31 of Fig. 6.

Claims (14)

1. Rotary mower (M), with a quick-change device (V) for at least one mowing blade (K) held in a pendulum manner, with a rotary body (R) in which a protruding mowing blade retaining bolt (H) is fixed for each mowing blade (K), and with a leaf spring (B) securing the mowing blade (K) arranged on the retaining bolt, which has a bore ( 15 ) which in the securing position (a) of the leaf spring encompasses a free end of the retaining bolt and can be elastically deformed relative to the rotary body (R) into a blade changing position (f) which releases the retaining bolt (H) at least by means of a changing tool (W) which can be inserted between the rotary body (R) and the leaf spring (B), characterized in that the retaining bolt (H) has a cylindrical collar ( 7 ) as a bearing point for the mowing blade (K) and, for additional securing of the mowing blade, a hook-shaped projection ( 9 ) which extends transversely to the axis (X) of the retaining bolt protrudes from the cylindrical collar ( 7 ). 2. Rotary mower according to claim 1, characterized in that the hook-shaped projection ( 9 ) points substantially inwards towards the center of the rotary body (R). 3. Rotary mower according to claim 1, characterized in that the hook-shaped projection ( 9 ) below the cylindrical collar ( 7 ) forms the end of the retaining bolt (H) facing away from the rotary body (R). 4. Rotary mower according to claim 1, characterized in that the hook-shaped projection ( 9 ) is offset eccentrically with respect to the cylindrical collar ( 7 ), and that between the cylindrical collar ( 7 ) and the hook-shaped projection ( 9 ) a contact surface ( 16 ) for the leaf spring (B) is provided, against which the leaf spring (B) rests with pre-tension in the securing position (a). 5. Rotary mower according to claim 4, characterized in that the hook-shaped projection ( 9 ), starting from the contact surface ( 16 ), has boundary surfaces ( 24 ) which recede obliquely in the direction of the axis (X) of the retaining bolt (H), preferably with an arcuate curvature ( 25 ) forming a crescent shape of the contact surface ( 16 ), and a flat underside ( 23 ). 6. Rotary mower according to claim 5, characterized in that the hook-shaped projection ( 9 ) has a free end ( 26 ) which has an arcuate curvature ( 27 ) approximately concentric to the axis (X) of the retaining bolt and which recedes obliquely towards the underside ( 23 ). 7. Rotary mower according to claim 1, characterized in that the upper side of the hook-shaped projection facing the rotary body (R) has a largely flat surface ( 29 ) with the shape of a circular ring segment, from the ends of which rounded flanks ( 30 ) extend essentially to the underside ( 23 ). 8. Rotary mower according to claim 1, characterized in that the projection (g) of the hook-shaped extension ( 9 ) over the cylindrical collar ( 7 ) is approximately 30% of the outer diameter (h) of the cylindrical collar ( 7 ). 9. Rotary mower according to claim 1, characterized in that the hook-shaped projection ( 9 ) has a width (k) which corresponds at most to the outer diameter (h) of the cylindrical collar ( 7 ), preferably is smaller than the outer diameter (h). 10. Rotary mower according to at least one of the preceding claims, characterized in that the distance (c) between the leaf spring (B) elastically deformed into the blade change position (f) and the rotary body (R) is dimensioned such that the mowing blade (K), when resting on the hook-shaped extension ( 9 ), can be tilted downwards with its cutting end ( 11 ) so far that it comes free from the cylindrical collar ( 7 ) on the side of the cylindrical collar ( 7 ) facing away from the hook-shaped extension ( 9 ). 11. Rotary mower according to claim 1, characterized in that the distance (d) between the hook-shaped projection ( 9 ) and the rotary body (R) is so large that in the blade change position (f) of the leaf spring (B), the mowing blade (K9) can be released from the cylindrical collar ( 7 ) until it rests on the hook-shaped projection ( 9 ) and abuts the rotary body (R) on the side facing away from the hook-shaped projection ( 9 ). 12. Rotary mower according to claim 1, characterized in that a largely flat counter surface ( 19 , 18 ) for a tool position holding surface ( 17 ) of the spreading leg (S), optionally widened by a round profile 33 ', is provided on the rotary body (R) and/or on the leaf spring (B) in predetermined engagement areas of a spreading leg (S) of the interchangeable tool (W). 13. Blade changing tool for a rotary mower (M) having a rotating body (R) and an elastically deformable leaf spring (B), characterized in that the tool (W) has at least one spreading leg (S) whose width is matched to the distance (c) between the rotating body (R) and the leaf spring (B) deformed into the blade changing position (f), which has a largely flat tool position holding surface ( 17 ) on at least one edge. 14. Blade changing tool according to claim 13, characterized in that the tool (W) is a two-leg C-shaped bracket ( 31 ), preferably with a tilting handle ( 33 ) made of round material, the C-legs of which form with their ends a gap ( 32 ) corresponding at least to the width of the mowing blade (K), and that the C-leg ends form spreading legs (S) which automatically position the tool (W) between the rotating body (R) and the leaf spring (B) in a predetermined mowing blade changing position (b) of the tool (W).