AU678003B2

AU678003B2 - Arrangement for the rotary actuation of a machine or plant part

Info

Publication number: AU678003B2
Application number: AU64742/94A
Authority: AU
Inventors: Erich Russ; Klaus Stoll
Original assignee: IMO Industrie Momentenlager Stoll and Russ GmbH
Current assignee: IMO Industrie Momentenlager Stoll and Russ GmbH
Priority date: 1993-06-19
Filing date: 1994-06-15
Publication date: 1997-05-15
Anticipated expiration: 2014-06-15
Also published as: JP2914476B2; AU6474294A; CA2127131A1; DE59400180D1; ATE136347T1; JPH07139594A; KR0144542B1; DK0631068T3; EP0631068B1; EP0631068A1; CN1101109A; CA2127131C; CN1048541C; ES2086978T3; DE9311316U1; KR950001146A

Abstract

Arrangement for the rotational drive of a machine or plant element, for example a crane, on a chassis or foundation, with a worm gear mechanism (3, 4), the housing (2) of which is secured on the chassis or foundation, the worm (3) of which can be set in rotation manually or by a drive motor and the worm wheel (4) of which is rotatably mounted in the housing (2), this being achieved by providing it with respective separate rolling-contact bearings (10, 11, 12) on both sides (6A, 6B) of its toothing (6) provided for engagement with the worm (3), the housing (2) being formed with a base part (2A) and a cover part (2B) which can be fixed in surface contact with the latter, at least one side face (6A, 6B) or untoothed side wall of the worm wheel (4) having a connecting projection which passes through the base or cover part (2A, 2B) and is designed for connection to the part to be rotated, and the two outer races (12) of the rolling-contact bearings resting against and/or being fixed on the respective walls of the base and cover parts (2A, 2B) of the housing (2), and the two associated inner races (10) each resting against and/or being fixed on the wall of the worm wheel (4). <IMAGE>

Description

COMMONWEALTH OF AUSTRALIA PATENTS ACT 1990 REGULATION 3.2 38463/28-ko Name of Applicant: Actual Inventor/s: Address for Service:

IMO-INDUSTRIE-MOMENTENLAGER

STOLL RUSS GMBH KLAUS STOLL; and ERICH RUSS E.F. WELLINGTON CO., Patent and Trade Mark Attorneys, 312 St. Kilda Road, Melbourne, 3004, Victoria.

r Invention Title: "ARRANGEMENT FOR THE ROTARY ACTUATION OF A MACHINE OR PLANT PART" Details of Associated Provisional Applications Nos: o o The following statement is a full description of this invention including the best method of performing it known to us.

1 9 1 Arrangement for the rotary actuation of a machine and plant part with worm gear The invention relates to an arrangement for the rotary actuation of a machine or plant part, for example of a crane, on a chassis or foundation, using a worm gear, the housing of which is secured on the chassis or foundation as hereinafter describei.

On known drives for mobile cranes, the pivoting movements are brought about, for example, by means of two hydraulic cylinders, which are formed as gear racks and are disposed to the left and right of a king trunnion mounting. The rotatory forces are transmitted onto a largely dimensioned pinion by means of the gear rack. Through this arrangement of the hydraulic cylinder drives, the gear used maintains considerable elongation in order to transmit high tilting moments.

A gear arrangement is known (DE-OS 34 46 438) wherein the worm wheel is mounted through only one cross roller bearing.

Through the single-shear bearing arrangement a tilting "moment arises through the drive (worm wheel, worm) This .has an adverse effect, because through this, supporting o: o capability of the single-shear bearing is lost and such high external forces cannot be transmitted. Furthermore, a higher tilting of the worm wheel arises through the singleshear bearing arrangement, which has a very adverse effect on the engagement relationships of the worm gearing. The single-shear bearing connects through a screw connection of oo.. the outer ring with the housing and of the inner ring with Sthe worm wheel. This is associated with extra expenditure of production and assembly.

Furthermore, arrangements with worm gears of approximately the initially named kind are known (USA-4 616 528, USA-3 710 640, EP-A-0 031 873, DE-A-33 21 854), on which the worm wheel in the gear housing is incorporated twice or twoshear. Two-shear bearing arrangement means that two separate bearings for the worm wheel, for example rolling bearings, are disposed coaxially to one another.

In the arrangements from the names sources, the worm gears are used without exception as a gear stage for valve applications, multiple drives particularly with d.c. motors or spindle lifting gears and spindle sliding gears. Common to these embodiments is that no particular arrangements are made against the influences of extraordinary tilting moments onto the shaft or axis of the worm wheel. The housings, as far as can be seen, are without exception one-pieced and on the basic of their structure, cannot contribute to guaranteeing or to at all increasing the solidity and stability of the axis or shaft of the worm wheel, which is used for example for output.

I In USA-3 710 640 as well as USA-5 116 291, there is used a separate shaft for the worm wheel which carries the roller bearings. This arrangement is susceptible to tilting moments.

The object of the invention is to provide a worm gear arrangement for rotary actuation, which on the one hand has a compact, space saving construction and on tV:, Kther hand has the capability to take up and transmit extraordinarily high external forces (axial and radial forces) and moments, above all tilting moments.

I II In accordance with the present invention, there is provided an arrangement for the rotary actuation of a machine or plant part, for example of a crane, on a chassis or foundation with a worm gear, a housing which is secured on the chassis or foundation, a worm which is rotationally displaceable manually or by a drive motor, and a worm wheel which is rotationally mounted in the housing, the worm wheel being provided at both sides of its gearing, which engages the worm, with a separate rolling bearing each, characterized in that the housing is formed with a base part and with a cover part which can be flatly fixed on top of said base part; that at least one end side or side wall of the worm wheel comprises a connection attachment which penetrates the base part or the cover part and is constructed for connection to the part to be rotated; that each of a pair of outer rings of rolling bearings lies against and/or is fixed to a corresponding wall of the base part and the cover part of the housing; and that each of a corresponding pair of inner rings lies against and/or is fixed to one of said sides of the worm wheel.

In preferred embodiments of the invention, said arrangement may be characterized in that: the rolling bearing arrangement of the worm wheel is achieved by means of a pair of angular bearings, with which rolling elements are each encompassed by the inner and outer rings with a peripheral section between 60 and 120 degrees, preferably 90 degrees; or the assembly of rolling bearings is disposed for bedding the *..worm gear, the inner and outer rings of which are slotted; or the assembly of rolling bearings is disposed on the worm wheel, the inner ring having a different, optionally smaller, diameter than the outer ring; or the base part and/or covering part of the gear housing and/or the worm wheel each comprise a recess into which the outer ring is disposed; or there are two or more actuatable worms, which engage with a common worm wheel; or the rolling bearings have several rolling ring elements to which rolling tracks are allocated and which are angularly inclined to each other; or the rolling bearings are designed with several rolling ring elements as double axial radial bearings known per se; or the worm engaging with the worm wheel is elongated and each are rotationally mounted in a common gear housing or frar.te; or a spring force opposing displacement is achieved with one or several spring elements, which rest against the housing wall and engage the worm; or the spring force opposing displacement is achieved with one or several spring elements which engage at the worm between "an end face of the thread and the adjacent rotationally mounted end section, and are supported against the housing wall of the gear; or 0* one or several of the spring elements are coil springs or Belleville springs penetrated by the worm, said spring elements optionally being combined as common tensionable spring sets; cr the cover p.rt and base part of the housing can be set on top of one another and/or screwed together in the direction of the worm wheel axis or parallel to the worm wheel axis; or cthe common support surfaces of the base part aid cover part of the housing are held together by fixing means, in particular, screwing means; or the fixing or screwing means extend parallel to the worm wheel axis; o: the connection attachment penetrates the cover part or the base part axially or parallel to the axis of the worm wheel; or the worm is provided at both ends with an axial and radial bearing; or the connection attachment is used for receiving and for carrying the machine or plant part.

In general, the gear housing is divided into an upper and lower part, one of the two parts being disposed by the connection attachment of the worm wheel for receiving or carrying the machine or plant part to be rotated. In that the *-outer rings of the two rolling bearings are each secured at an upper and lower part of the housing and the corresponding inner rings are secured at the worm wheel, and following that, the upper part and lower part are tightly screwed together to form the entire housing, a compact, space saving and solid unit results, in which the gear and bearing arrangement are constructionally integrated into one another. In ooe particular, the rolling bearings are braced and additionally stabilized by this. In this way the part to be rotated with extraordinary weight can be assembled on the worm wheel, whereby not only high axial and radial forces, but also high tilting moments can be taken up in an operationally safe way.

The gear arrangement according to the invention is suitable above all for directly driving machines and plant parts. It can replace the known rotatory connections and pinion with intermediate gearing, with less constructional expenditure and increased reliability. In that the two-shear bearing arrangement of the worm wheel cooperates, according to the invention, with the housing parts which are screwed together, a worm wheel with simple construction and large cost saving can be taken up in the gearing housing, which is also robust relative to tilting moments.

Due to the closed housing, the drive arrangement according to the invention is largely screened against parasitic induction from the surroundings, which increases the ease of maintenance. No such high demands of constructional S exactness need be placed on the connection construction with the connecting attachment, since the drive arrangement according to the invention has a high intrinsic rigidity to start with. This results, among other things, from the measure according to .the invention that, on the one hand the worm wheel and on the other hand the upper and lower part (base or cover part) of the gear housing are each used as carrier elements for the hardened raceway shells (inner and outer rings) of the two-shear bearing arrangement.

Furthermore, the two housing parts are rigidly connected with one another or fixed to each other. The bearings of the worm wheel can be four-point bearings (ball), as well as roller bearings. The bearing forces are transmitted by means of further securing screws at outer flanges of the housin or the like, into the surrounding construction. Due to the measures according to the invention, thie housing and the worm wheel are in the position to take up the high external forces stemming from the heavy machine and plant parts, said high external forces being transmitted by means of the bearings. The upper part or cover part of the housing can for example take over the function of taking up the external tensile forces. Furthermore, the housing can hold the bearing free of backlash or hold the initial tension.

According to a particular embodiment, the housing parts lie together via sealing means in order to be sealed against the environment.

The basic principle according to the invention of spatially extending, as it were, the bearings of the highly loaded worm wheel in the applications contemplated, corresponds to a further development of the invention according to which the worm wheel is mounted rotationally by means of two separate inclined rolling bearings, on which the rolling S elements are each encompassed, by the inlays or by the inner and outer ring, with a peripheral section between 600 and 1200, preferably approximately 900. This excludes the way known per se (see above) of arranging the worm wheel with a single cross rolling bearing. Radial, axial loads and tilting moments can be advantageously taken up by means of the two angular ball bearings.

a. To achieve a constructively simple coupling of the part to be rotated to the gear arrangement it is suggested, according to another further development of the invention, that at least one end face or other non-geared side wall of 3 the worm wheel is specifically formed to connect with the part to be rotated, be it through a ring of bores to be screwed, or through hock-shaped locking elements for example or latching devices. A one-piece connection between worm c wheel and the part to be rotated is also conceivable within the framework of the invention.

The manufacturing costs are lowered when, according to another further development of the invention, the inlays or inner and outer ring of the rolling bearings are radially slotted throughout. The possibility is then created of not only manufacturing the inlays economically from a single run, but of also being able to spread the inlays out quickly during the incorporation or the assembly.

By using rolling bearings, the outer ring is expediently fixed at the inner wall of the gear housing and the inner ring at the worm wheel to be rotated. The rolling bearings are connected by the gear cover to form one unit.

So that as high a torque as possible can be transmitted, two or more worms according to another development of the invention are disposed which act upon the (common) worm wheel.

With extreme loading it can also be expedient within the framework of the invention to embody rolling bearings with several rolling ring elements which roll off tracks and which are angled to bach other. Here for example, a rolling ring element can be provided exclusively for transmitting S radial forces and each further rolling ring element for transmit.ing axial forces in both directions of moments.

The first rolling element set would roll off cylindrical running tracks whereas the two other rolling ring elements roll off on flat surfaces perpendicular thereto. Such bearing modules arc known per se as double axial radial bearings.

In known worm drives, particularly when they are not used purely as transmitting drives but in the sense of the type according to the invention for directly driving machines and

I

plant parts, (DE-OS 34 46 438), the following problem can easily arise: The rotating worm wheel must sometime be braked in the shortest possible time. since, as a rule, a lot of mass moves with the rotating worm wheel in the named applications, kinetic energy is to be converced to a large extent. As a result of this, it can happen when braking quickly, that the worm wheel gearing or the worm thread engaging it, breaks.

Consequently, the further problem within the framework of the invention is raised, of intercepting dynamic forces arising during the running and in particular the braking of the worm wheels which are coupled with a machine part and to compensate such that a destruction of the gear engagement between worm and worm wheel is prevented. To achieve this, in a worm gear arrangement with the initially named features according to the invention, it is suggested that the worm is not only rotationally mounted, but is also mounted displaceably in its longitudinal direction against spring force (linear). In other words, one or several spring elements are disposed within the gear housing such that they S stand in the way of the linear displacement of the worm with their spring force. This can be expediently achieved in that the spring element or elements on the one hand are supported or engaged against the housing wall and on the other hand at the worm. With this embodiment according to the invention, mass forces of the rotating parts can be compensated without the gearing being damaged due to overloading. A shock-type braking is avoided.

Spring devices are advantageously combined in the set after Go.

3 one or both ends of the worm thread, for example one or IO several screws cr adjacent Belleville spring washers, which each engage between a thread end side and the worm shaft end while supported against the housing wall.

I

With the spring compliance according to the invention, the worm is allowed a certain stroke within the housing or framework by means of which braking forces and deceleration loading can be balanced out or compensated.

The worm in each case is advantageously mounted on both sides at its ends with a radial and axial bearing, because through this the external mass forces or impacts can be softened and pretensioned Belleville spring washers can be disposed between the axial bearings and the worm.

With the aim of strengthening the robustness against tilting moments, an expedient embodiment exists in that the cover and base part of the housing are placed on top of each other in the direction of the worm wheel axis or parallel thereto.

The adjacent support surfaces of the two housing parts increase the solidness and then prevent the tilting together of said housing parts, a stable support being also guaranteed for the outer rings of the two-shear worm wheel bering arrangement. Advantageously the common support surfaces of the housing parts are dimensioned such that they :'20 can be interspersed by fixing means, particularly screw S means. The tilting is further reacted against when the fixing or screw means extend parallel to the worm wheel axis, the common support surfaces of the housing parts being pressed together with maximum force. By this means the stability of the bearing arrangement is optimized.

Within the framework of the invention the connecting attachment of the worm wheel intersperses the cover or base part or one of the two housing parts axially or parallel to the axis. By this means the connection extension can particularly easily be used for receiving and for carrying the machine or plant part to be rotated.

The worm gear actuation drive arrangement according to the invention can be used particularly in mobile, construction, harbour and industrial cranes, excavators, lifting platforms, deep shovel dredgers, concrete mixers, fork lifting ancillary equipment, revolving welding tables and concrete pumps, for forming the necessary rotatory connection in each case. Further areas of application for the drive arrangement according to the invention are swinging devices for grabs, track pinch bars, working load turning machines, ancillary manipulators, swinging stacker equipment, car park systems, swinging lifting platforms, motor vehicle winches and wall winches, body bolsters for heavy road vehicles, steering drive units for heavy goods vehicles, machines for packing and filling, labelling, sorting, mixing and stirring works, thickening plants and research plants for discharge water and mud treatment, construction machines, drag bearings, dredger-loaders, universal dredgers, robots, f.-ding machines, rotary indexing tables and reversible clamping devices.

Further details, features and advantages on the basis of the invention result from the sub claims as well as the following description of a preferred embodiment of the invention with reference to the drawings, in which: Fig: 1 is a perspective illustration of a drive arrangement with worm gear, Fig: 2 is a plan view according to the direction II in 2 5 Figure 1, Fig: 3 is a section according to the line III III in Figure 2 Fig: 4 is an enlarged illustration of the details IV in Figure 3 and Fig: 5 is the ball bearing used in the arrangement according to Figures 1 4 in axial plan view.

According to Figure 1 the worm gear 1 for the actuation arrangement used according to the invention, comprises a gear housing 2, (Fig. 3) with a base part 2a, in which a worm 3 and a worm wheel 4 are mounted rotationally. The base part 2a has a support surface 20, interspersed by a row of inner thread bores 21 axially parallel to the worm wheel 4. At the straight front side of the base part 2a largely bent in the example; a projecting securing flange 22 is formed, over the securing holes 23 of which a fixing to a foundation or chassis (not shown) can be effected. The worm 3 which engages with the gearing 6 of the worm wheel 4 by means of its screw-shaped thread 5, is provided for coupling with a torque drive motor (not shown) The worm wheel 4 has at its end side an axially parallel or cylindrically projecting connection attachment 7, in the end wall 8 of which a multitude of securing elements, e.g. screw bores 9 are formed in rows in the direction of the periphery or in rings. These are used to secure a machine or plant part to be rotated (not shown). Lying on the end side of the worm wheel-gearing 6, is the smaller inner ring 10 of an angular ball bearing (Figure 4) visible in Figure 1. By inserting a multitude of balls 11 (Figures 3 and 4) into this inner ring 10 and setting on of a (larger) outer ring 12, the complete angular ball bearing 10, 11, 12, is formed.

As can be seen from Figure 1 and above all from Figure 2, a stop shoulder 13 in each case at a distance from the two end faces of the worm thread 5 is raised and projects in an annular fashion around the worm shaft. Between each of these stop shoulders 13 and the worm end sections 14 mounted S.0Q rotationally in the wall of the housing 6, one or several sets 15 of a multitude of individual Belleville spring washers 16 are disposed particularly such that they clamp.

The Belleville spring washers 16 or the corresponding sets are slipped onto the worm 3 on both sides of the worm thread 5 via their inner recesses until they abut. the corresponding stop shoulder 13.

The Belleville spring washers 1G are annular platelets which, according to the partial cross-section illustration in Figure 2, increasing from their planes, deviate in their two dimensional annular areas by an inclined angle. within a spring set 15 at ).east two such Belleville spring washers 16 are laid mirror-imaged to one another suchi that onlyv their outer edges, which project the most from the said annular plane area, make contact. This deviation is elastically reversibly reduced during axial force, for example, due to transient deceleration or acceleration of the worm wheel 4. The possibility of linear stroke movements 17 for the wormi 3 in the gear housing 2 results from this. By means of these stroke movements 17 of the worm 3, dynamic forces arising with abrupt acceleration or deceleration of the worm wheel 2, for example when braking or running, can be takenI up on both sides by the spring sets so that an abrupt braking of load is possible without dest~ -tying the gearing 6 and/or the thread According to Figure 3 an (upper) cover part 2b is to be set flatly onto the support surface 20 (Fig. 1) of the lower base part 2a to form the entire housing 2. connection screws :24 which are screwed into the inner thread bores 21 of the base part 2a and engage the cover part 2b by means of f lush through bores, are used to rigidly f ix together parlL 2a and part 2b. The worm wheel 4 is mounted such thaL it is rotatable opposite the gear housing 2 through two ball see* bearing sets 10, 11, 12, which each lie on one of the two end sides 6a, 6b of the worm wheel gear:ing 6. With this, '00 the smaller inner ring 10 is always fixed at the to 0:60: corresponding end side Ga or 6b of the worm wheel gearing 6 and the larger outer ring 1.1 at the inner wail of the housing 2. TherefEore, in that the bearing arrangement of the worm wheel 4 is spatially extended by the division of the bearing arrangement, each into a separate ball bearing set 10, 11, 12 for the end sides 6a, 6b at the worm wheel gearing, radial loads Frad axial loads Fax and tilting moments Mk can be taken up to an extraordinary extent, the torque Md of the worm wheel 4 required for the part to be driven, remaining largely unimpaired around its centre axis 18.

This advantageous effect of the two-shear bearing arrangement is further conveyed by the use of angular ball bearings according to Figure 4. The inlays or inner and outer rings 10, 12, each surround the bearing balls 11 with only a peripheral section of approximately 900. If these are disposed flush according to Figure 3, coaxially or parallel to the axis, to the centre axis 18, a tilting moment Mk can be taken up with greater operational certainty by two cooperating bearings 10, 11, 12 at each one end side Ga, 6b of the worm wheel.

In Figure 5 a complete angular ball bearing set 10, 11, 12 is shown in plan view. Here, radial slits 19 can be seen which intersperse each of the inlays or smaller and larger rings 10 or 12.

The matter contained in each of the following claims is to be read as part of the general description of the present invention.

Claims

1. Arrangement for the rotary actuation of a machine or plant part, for example of a crane, on a chassis or foundation with a worm gear a housing which is secured on the chassis or foundation, a worm which is rotationally displaceable manually or by a drive motor, and a worm wheel which is rotationally mounted in the housing the worm wheel being provided at both sides (6a, 6b) of its gearing which engages the worm with a separate rolling bearing (10, 11, 12) each, characterized in that the housing is formed with a base part (2a) and with a cover part (2b) which can be flatly fixed on top of said base part that at least one end side or side wall (6a, 6b) of the worm wheel (4) comprises a connection attachment which penetrates the base part or the cover part and is constructed for connection to the part to be rotated; that each of a pair of outer rings (12) of rolling bearings lies against and/or is fixed to a corresponding wall of the base part .i and the cover part (2a, 2b) of the housing and that each of a correspcnding pair of inrer rings (10) lies against and/or is fixed to one of said sides (6a, 6b) of the worm wheel (4)

2. Arrangement according to claim 1, characterized in that the rolling bearing arrangement of the worm wheel is achieved by means of a pair of angular bearings, with .which rolling elements (11) are each encompassed by the *a inner and outer rings (10, 12) with a peripheral section between 60 and 120 degrees, preferably 90 degrees.

3. Arrangement according to claim 2, characterized in that the assembly of rolling bearings (10, 11, 12) is disposed for bedding the worm gear the inner and outer rings 12) of which are slotted.

4. Arrangement according to claim 2 or 3, characterized in that the assembly of rolling bearings (10, 11, 12) is disposed on the worm wheel the inner ring having a different, optionally smaller, diameter than the outer ring (12) Arrangement according to any one of the preceding claims, characterized in that the base part and/or covering part of the gear housing and/or the worm wheel each comprise a recess into which the outer ring (12) is disposed.

6. Arrangement according to any one of the preceding claims, characterized by two or more actuatable worr.s, which engage with a common worm wheel.

7. Arrangement according to any one of the preceding claims, characterized by rolling bearings with several rolling ring elements to which rolling tracks are allocated and which are angularly inclined to each other.

8. Arrangement according to claim 7, characterized in that the rolling bearings are designed with several rolling ring elements as double axial radial bearings known per se. •oes

9. Arrangement according to any one of the preceding claims, characterized in that the worm engaging with the worm wheel is elongated and each are rotational2y mounted in a common gear housing or frame. S

10. Arrangement according to claim 9, characterized in that a spring force opposing displacement (17) is achieved with one or several spring elements (15, 16), which rest against the housing wall and engage the worm (13) 14

11. Arrangement according to claim 9 or 10, characterized in that the spring force opposing displacement is achieved with one or several spring elements (15, 16) which engage at the worm 13) between an end face of the threa,' and the adjacent rotationally mounted end section (14), and are supported against the housing wall of the gear

12. Arrangement according to claim 10 or 11, characterized in that one or several spring elements (15, 16) are coil springs or Belleville springs (16) penetrated by the worm, said spring elements optionally being combined as common tensionable spring sets.

13. Arrangement according to any one of the preceding claims, characterized in that the cover part and base part (2a, 2b) of the housing can be set on top of one another and/or screwed together in the direction of the worm wheel axis (18) or parallel to the worm wheel axis (18).

14. Arrangement according to any one of the preceding claims, characterized in that the common support surfaces (20) of the base part and cover part (2a, 2b) of the housing (2) are held together by fixing means, in particular, screwing means (21, 24) Arrangement according to claim 14, characterized in that the fixing or screwing means (21, 24) extend parallel to the worm wheel axis (18)

16. Arrangement according to any one of the preceding claims, characterized in that the connection attachment (7) penetrates the cover part or the base part (2a, 2b) axially or parallel to the axis of the worm wheel (4) 0

17. Arrangement according to any one of the preceding claims, characterized in that the worm is provided at both ends with an axial and radial bearing.

18. Arrangement according to any one of the p2eceding claims, characterized in that the connection attachment is used for receiving and for carrying the machine or plant part. DATED this 5th day of March 1997 IMO-INDUSTRIE-MOMENTENLAGER STOLL RUSS GMBH, By its Patent Attorneys, E F. WELLINGTON CQ., (Bruce Wellington) a o a a. *9 a a a.* A/KA/4101 I Abstract The present invention provides a worm gear arrangement for rotary actuation, which on the one hand has a compact, space -'/ing construction and on the other hand has the capability to take up and transmit extraordinarily high external forces (axial and radial forces) and moments, above all tilting moments. In the arrangement, the gear housing is divided into an upper and lower part, one of the two parts being interspersed by the connection attachment of the worm wheel to the machine or plant part to be ictated. The outer rings of the rolling bearings are secured at upper and lower parts of the housing and the corresponding inner rings are secured at the worm wheel. The upper and lower parts of the housing are tightly secured together to form a compact, space saving and solid unit in which the gear and bearing arrangement are constructionally integrated into one another. *i0 e *go• o• L YI _B