CA1285143C

CA1285143C - Riding mower

Info

Publication number: CA1285143C
Application number: CA000513211A
Authority: CA
Inventors: Rolf Andres Gunnar Johansson
Original assignee: Husqvarna AB
Current assignee: Husqvarna AB
Priority date: 1985-08-08
Filing date: 1986-07-07
Publication date: 1991-06-25
Anticipated expiration: 2008-06-25
Also published as: FI863237A0; US4809489A; SE8503747D0; JPH0671373B2; DK161004B; SE8503747L; SE454127B; JPS6342616A; NZ216778A; FI81711C; EP0213096A1; DK371286D0; DK371286A; EP0213096B1; DK161004C; AU5948386A; ATE63195T1; DE3679120D1; FI81711B; AU594063B2

Abstract

ABSTRACT

The invention relates to a mower comprising a chassis which is provided with an engine. The chassis consists of a front and a rear section each section being provided with a pair of wheels and the front section supports a cutting attachment. The front and at least a part of the rear section are pivotally connected to each other so that they can be turned mainly about a vertical steering axis and about a mainly horizontal swinging axis. The steering axis (29) and the swinging axix (42) is placed considerably closer to the wheel axis of the rear section (13) than the wheel axis of the front section (12) preferably so that the distance (a) between the steering axis (29) and the wheel axis of the rear section (13) is less than 1/3 of the distance (b) betweenthe two wheel axis.

Description

~,~.?d ~ S~l~3 ~ i9 invention relates to a mower having a ChaSSi8 with an enyine ancl comprising a front and rear section, each section being providecl with a pair of wheels, the front section supporting a cutting attachment, the front section and at least fl part of the rear section being pivotally connectecl to each other so that they can be turned about a mainly vertical ateering axis and about a mainly horizontal swinging axis.
Mowers of the riding type are previously known. Such machines can be provided with front mounted cutting attachrnents and cutting attachments which are centrally placed between the front- and rearwheels respectively.
The engine can be placed in front of or behind the driver and further there are front wheel- and rearwheel 3teering and driving. Each type llas its own advantages and drawback~. For instance mowers with centrally placed cutting attachments generally have the drawback that the front wheel pressea down the grass before lt reaches the cutting attachment which mean3 that parta of a lawn are badly cut. A mower having a front mounted c~ltting attachment, rear mounted engine and rear wheel steering gives a good survey of the cutting attachment and the surface to be cut whereas the drawback i5 a large turning radius since the steering angle ia limited with the respect to the friction between the lawn and the steering wheels. A rear wheel driven machine with the engine at the r ear, centrally placed cutting attachment and with front wheel steering gives advantages with respect to the transrnission because of the short distance between the engine and driving wheels and cutting attachment respectively but gives an even large turning radius since the centrally placed cutting attachment creates a larges wheel basis then machines having front mounted attachments. In order to shorten the time during shunting in connection with turnings it i~ desirable that a machine has as short turning radius as possible.
In a type of machine which is a rather good compromise between dif ferent wishes the chassis comprises two sections which are pivotally connected to each other half way between the front and rear wheels. The front section oP the chassi~ suppor~s the two front wheels which are rnounted on separate shafts, the cutting attachment which is placed ahead of the front wheels and the operator. The rear Yection supports engine with gear box, differential gearing and rear shaft, the steering being effected by turning the rear section with respect to the front section about a vertical steering axis.
The pivot point i~ in this machine so designed that turning the rear section .

~.2~3S~43 with respect to the front seckion also can he effected about a swinging axis which is directed in the travelllng direction of the mower and horizontally PlaGed on the front section in order to make it possible for the wheels to follow irregularities on the ground.
Even if the maahine descrlbed above ln most respec-t has rather good characteristics, its turning radius is after all limited to someth:Lng which corre~ponds to about 45 turn of angle of the rear section. This depends on that the rear wheels - with the reasonable length o~ the machine - when being further turned would ~et in touch with the front wheels and that ~urther turning o~ the wheels would lead to too large variation in the gxound pressure between the two driving wheels because o~ khe positlon of the swinging axis. At a certain steerin~
angle the ground pressure on the inner wheel becomes so small that driving ceases. The ground pres~ure of this wheel can even become negative that is the wheal is lifted from ground which causes the risk ~or tippiny. Moreover the cutting attachment of thls machine cannot be driven directly by one slngle belt from the engine since the distance between engine and cutting attachment changes with the steerlng ànyle. Further drawbacks are that there is a demand for operating devices on the engine following its movement and that a certain undesirahle self~uiding is achieved because the grass during cutting brakes the knifes which cauæes a moment between the two sections of the machine.
The purpose of this invention is to achieve a mower which gives maximum passability by reducing the turning radius with respect to known machines at the ~ame time as the risk for slipping is reduced to minimum as is also the risk for tipping and where the other drawbacks referred to above are eliminated. This purpose is achieved with the device according to the invention as it is defined in the following claims.

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A~c~ordi.n~ to one broad aspect of the present lnven-tion, there is providecl ln an englne-dri~en rldiny mower havin~ a chassis provided wlth ~eparate front ~nd rear sections, an en~ine mounted on said rear se~tlon, a cutting attachment supported by sald ~ront section and driven by said engine, the lmprovement comprising a pair of front wheels operatively connected to said front sectlon and a pair of rear driving wheels operatively connected to said rear section, said rear driviny wheel~
having an axis, means for steerlng said rear driving wheels and including a vertical steering axis about which said rear driving wheels turn, ~aid vertlcal steering axi~
belng located in the rear o~ ~aid mower ahas~is ak a d:Lstance ~rom the rear whee:L axis whiah is less than 1/3 o~ the distance between the ~ront and rear wheel axes, and a horizon~al swinging axis whlah is substantially perpen-dicular to said rear wheel axis, said horizontal swinging axis being placed at said vertical axis location and additionally positioned centrally between said driving wheels, and said engine belng provided with an output sha~t that is concentric with said verklcal steering axis.
An embodiment of the invention will now be described with reference to the accompanying drawings where figure 1 is a longitudinal vertical section of a device according to the invention whereas Fig. 2 is a longitudinal vertical section of the rear part of the device according to the inventioll and Fig. 3 is a vertical section of a modified embodiment according to the invention.
As appears from Fig. 1 and 2 the mower compri~es a chassis generally denoted 10. The chassis has a front pair of wheels and a rear pair of wheels 11 and comprises two sections 12 and 13 respectively. The front section 12 supports a cutting a~tachment schematically deno~ed 1~, a seat 15 for the driver, necessary manoeuvre devices and a battery 16, engine 17 and petrol tank 18. The rear ~ection 13 supports a gear box 19 with differential gear and a rear shaft 20 which drives a rear pair of wheels 11.

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S.'L~3 In order to SUppOIt the engines 17 the rear part of the chas3is front section 12 ia shaped as a support plate 21 with a hole 22 through which the output shaft 23 of the engine extends vertically downwards. To the supporting plate 21 an outer ring 24 of a ball bearing with large diam0ter is fastened by means of several screws 25. The inner ring 26 of the ball bearing is by means of screws 27 connected to a turning plate 28. The turning plate moves about a steering axis 29 and has a hole through which the output shaft of the engine extends. The output shaft 23 of the engine at its lower part supports a hub 3û
which has an upper pulley 32 with comparatively small diameter for driving the wheels of the mower the pulley being fixed to a sleeve 33 which i3 concentric to the output shaft 23 and which supports a lower pulley 34 wlth a comparatively large diamater intended to drive the cutting attachment.
The pulleya 32 and 34 are fastened to the output shaFt 23 of the engine by means of a bolt 35 and a washer 36. ~hus, the t~lrning plate 2a is turnable about the output aha~t 23 of the engine and haa a bearing holder 37 which by means of bolts 3a is fastened to the turning plate 28 as well as to a bracket 39 on which a steering plate 40 i9 provided by means of bolts 41. The steering plate 40 i9 via a wire connected to the steering wheel of the mower.
In the bearing holder 37 a dowel 42 is turnable secured. The dowel extends horisontally rearwards and one of its ends has a clamp 43 which is an intergrated part of the rear section 13 of the chassis whereas its front end has a locking washer 44 which prevents the dowel from falling out of the bearing holder 37. The dowel rests in two sliding bearing 45 which are pressed into the bearing holder.
The gear box has an input shaft 46 which is vertically placed and provided with a pulley 47 which i8 driven from said upper pulley 32 by means of a belt 4a.
As appears from the figure the upper pulley 32 and the pulley 47 on the input shaft of the gear box are situated in the same horisontal plane as the dowel 42 in order to reduce the tendency of the belt to pull off the pulleys when turning is effected about the horisontal axis.
By acting on the steering wheel the steering plate 4û will be turned so that the rear section 13 turns about the vertical shaft of the engine 23. Since the rear section 13 is comparatively short compared to the front section 12 and in combination with the position of the pivot 37, 42, 45 on the short chassis section, larger steering angles or larger variations between the ground pressure of the driving wheels can be allowed without the,risk for tipping than in previously known arrangements which in turn means reduced turning radius. Any irregularities on the ground will as said above be taken up as a turning movement of the rear shaft about the horisontal longitudinal axis.

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~ . ' '','~ ' ', ~ ~35~3 The device shown in Fig. 3 clifFers frorn what haa been shown in Fig. 1 mainly because the engine is placed on a supporting plate 49 which is a part of the rear section 13 of the chassis, the sLIpporting plate 49 and engine 17 together being turnable about the vertical axis 50 coinsiding with the shaft of the engine. The supporting plate is via a swinging axis 51 fastened to one of two to each other linked parts 52, 53 which means that the rear shaft 2n may achieve different angle positions with respect to the horisontal plane.
The turning plate moves about the vertical steering shaft 29 which coinsides with the motor shaft 23, the steering axis being placed cDnsiderably closer to the wheel axis of the rear section 13 than the wheel axis of the front section 12. Preferably the distance a between the steering axis 29 and the wheel axis of the rear section :13 la less than 1/3 of the di~tance b between the two wheel axis.

Claims

1. In an engine-driven riding mower having a chassis provided with separate front and rear sections, an engine mounted on said rear section, a cutting attachment supported by said front section and driven by said engine, the improvement comprising a pair of front wheels operatively connected to said front section and a pair of rear driving wheels operatively connected to said rear section, said rear driving wheels having an axis, means for steering and rear driving wheels and including a vertical steering axis about which said rear driving wheels turn, said vertical steering axis being located in the rear of said mower chassis at a distance from the rear wheel axis which is less than 1/3 of the distance between the front and rear wheel axes, and a horizontal swinging axis which is substantially perpendicular to said rear wheel axis, said horizontal swinging axis being placed at said vertical axis location and additionally positioned centrally between said driving wheels, and said engine being provided with an output shaft that is concentric with said vertical steering axis.

2. A riding mower as claimed in claim 1 wherein said rear section is provided with a gear box with a differential gear, a rear shaft for transmitting a driving force to said rear pair of wheels, and a belt wherein the transmission of force between the engine and gear box is created by said belt which is located in the same plane as said horizontal swinging axis.