worm and worm wheel gearbox pdf

Worm And Worm Wheel Gearbox Pdf

File Name: worm and worm wheel gearbox .zip
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Published: 29.04.2021

A worm gear clutch mechanism comprising a worm shaft 10 , an output shaft 16 having a worm wheel 11 , and means to move the worm shaft relative the worm wheel, the worm shaft being movable about a tilt axis that is substantially perpendicular to the longitudinal axis of said worm shaft 10 so that the worm shaft is movable into and out of engagement with the worm wheel.

A worm gear is a gear consisting of a shaft with a spiral thread that engages with and drives a toothed wheel.

Worm Gears Explained

A worm gear clutch mechanism comprising a worm shaft 10 , an output shaft 16 having a worm wheel 11 , and means to move the worm shaft relative the worm wheel, the worm shaft being movable about a tilt axis that is substantially perpendicular to the longitudinal axis of said worm shaft 10 so that the worm shaft is movable into and out of engagement with the worm wheel.

The present invention relates to a mechanism for the provision of a positive drive engagement and disengagement means suitable for slow turning high torque driveshafts for any application where it would be desirable to disconnect a driveshaft from a drive train to enable the driveshaft to freely rotate. Worm drive gearboxes have long been recognised as the most common and compact method to achieve high ratio speed reductions. An axis of the worm gear shaft is positioned perpendicular to a worm gear wheel and at a fixed and precise distance to provide accurate engagement of a worm of the worm gear shaft with gear teeth of the worm gear wheel.

The worm is a spiral groove which is machined into a portion of the worm gear shaft, the worm or groove engaging with corresponding teeth on the worm gear wheel.

Rotation of the worm gear shaft propels the teeth on the worm gear wheel along the pitch of the worm, thus rotating the worm gear wheel about its axis. Limitless speed reductions can be achieved by altering the worm shaft and worm wheel diameters in conjunction with the worm screw pitch distance and the number of gear teeth in the worm gear wheel.

In a traditional worm drive gearbox, the worm gear shaft and the worm gear wheel normally rotate on bearings which are fixed within the body of the gear housing and therefore the gears are constantly engaged with no means of disengagement. The compact nature of a worm drive gearbox as a means to achieve high ration speed reductions makes it a popular choice for a wide rang of industrial and commercial applications however many of these applications would benefit from a means of engaging and disengaging the drive.

One such application would be a pedestrian operated machine whereby the high ration speed reduction provides a slow turning wheel axle which enables the machine to be propelled at walking pace however it would be extremely beneficial if a means for disengaging the worm gear wheel from the worm shaft drive was provided so as to enable the machine to be wheeled freely by an operator.

The driveshaft is mounted on a pair of eccentric mounts such that rotation of the mounts effects the engagement and disengagement of the worm from the bull gear. It is therefore an object of the present invention to obviate or mitigate the above problem by providing a worm gear clutch mechanism having an engagement and disengagement facility which is versatile in operation, inexpensive to produce and lends itself to a wide range of applications.

Accordingly, the present invention provides a worm gear clutch mechanism comprising a worm shaft and an output shaft having a worm wheel, the worm shaft being movable about a tilt axis that is substantially perpendicular to the longitudinal axis of said worm shaft, so that the worm is movable into and out of engagement with the worm wheel.

Conveniently, activation means is provided proximate the worm so that said worm can be controllably brought into and out of engagement with the worm wheel.

Advantageously, the tilt axis may be located within or externally of a gearbox casing which encases the clutch mechanism, dependent on the proposed use of the mechanism. Preferably, the worm shaft is carried in a worm arm. Preferably, the worm arm comprises two spaced apart parallel side walls secured together at each of their respective ends with the shaft carried between the two end walls and parallel to the two sides.

Alternatively, the worm arm may comprise one side wall or may comprise a tubular member through which the input driveshaft extends.

Alternatively also, the worm arm at the end or near to the outer end of the driveshaft has an engagement adjuster screw mounted therebelow to rest on an engagement axle when the worm wheel and worm shaft are disengaged.

An engagement lobe is desirably provided on the axle to engage the adjuster screw when the axle is rotated. Preferably, the worm shaft is mounted eccentrically at one end in a rotatable engagement coupling that is movable so as to bring the worm shaft into and out of engagement with the worm gear wheel. Other aspects of the invention are defined in the appended claims which are incorporated into the description by way of reference. Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:—.

Referring to the drawings, a worm gear clutch mechanism includes an output shaft 16 having a worm wheel 11 and a worm gear shaft 10 , the worm gear shaft being movable about a tilt axis that is substantially perpendicular to its longitudinal axis and which is located at a position remote from the output shaft 16 so that the worm can be moved into and out of engagement with the worm wheel.

Means to move the worm shaft into and out of engagement with the worm gear wheel 11 are provided proximate the worm. The tilt axis of the worm shaft can be located within or external of a gearbox casing encasing the mechanism depending on the proposed use of the mechanism. With reference to FIG. The worm arm is pivotally attached via gearbox cross-shaft bearings 27 to an input driveshaft in the form a gearbox cross-shaft 28 which extends from a suitable drive means or motor.

Input drive is transferred from the gearbox cross-shaft 28 to the worm gear shaft 10 via bevel gears 13 A one of which is fixed to the end of the worm gear shaft and the other on the centre portion of the gearbox cross-shaft between the said gearbox cross-shaft bearings. Means to move the worm gear shaft 10 into engagement with worm wheel 11 comprises an engagement axle 20 rotation of which via an engagement lever 23 causes worm arm 12 A to tilt about a longitudinal axis of the gearbox cross-shaft axis raising and lowering the worm arm 12 A by virtue of a engagement lobe 21 which acts like a cam in contact with an engagement adjuster screw The tilting movement of the worm arm 12 A engages and disengages the worm gear shaft 10 from the worm gear wheel 11 as illustrated in FIG.

When the worm gear wheel 11 and worm shaft 10 are engaged, lateral movement of the worm gear shaft in relation to the worm gear wheel is prevented by a lateral support pad 32 which is fixed to the worm arm 12 A on either side of, and in contact with, worm gear wheel As shown in FIGS.

The gearbox cross-shaft has been replaced by cross stub axle 28 A about whose longitudinal axis worm arm 12 A tilts by virtue of gearbox cross-shaft bearings The input drive via drive shaft 39 to the tilting worm shaft 10 is provided by universal drive coupling 38 with a seal between tilting worm arm 12 A and the gearbox casing 34 provided by flexible seal As illustrated in FIGS.

Again, like parts are denoted by like numerals. Worm arm 12 A has been replaced by a worm saddle 41 which extends over the worm portion of the worm shaft and which contains a radial thrust bearing 26 at each end on which the worm shaft rotates.

Lateral support pads 32 and engagement adjuster screw 22 are attached to the said worm saddle in the same manner and for the same purpose as on the worm arm 12 A. Rotation of engagement axle 20 via engagement lever 30 causes the worm gear shaft 10 to tilt about an axis of universal drive coupling 38 thereby raising and lowering the worm saddle 41 to facilitate engagement and disengagement of worm shaft 10 with the worm wheel Tee input driveshaft 39 rotates about its axis by virtue of driveshaft bearings 40 which are contained in the gearbox casing 34 and provide a non-tilting input drive for the tee drive gearbox.

Various mechanisms can be used to tilt the worm gear shaft to engage and disengage drive. The outside diametric surface of eccentric housing 42 is offset from the self aligning radial bearing contained within. The outside diametric surface is located and supported by gearbox casing 34 so when the eccentric housing is rotated by means of engagement lever 30 , the worm gear shaft is moved in an arc so as to engage and disengage worm gear wheel 11 as shown in FIG.

Self-aligning bearing block 43 provides the pivot point for the worm gear shaft to enable engagement and disengagement with the worm gear wheel when the universal joint is located external to the casing The ball-joint characteristics of the universal drive coupling 38 and the self aligning bearing block 43 enable the arcuate movement imparted by eccentric housing 42 at the opposite end of the worm gear shaft 10 to tilt the said worm gear shaft to engage and disengage drive.

Input drive to the tilting worm gear shaft 10 is provided by driveshaft 39 which couples to worm shaft 10 via universal drive coupling 38 as illustrated in FIG. Parallel drive gearboxes such as illustrated in FIG. The gearbox cross-shaft 28 can also be utilised as a non-reduced speed output or auxiliary driveshaft. This extension could be utilised for example, in a ground working machine application, to enable the auxiliary driveshaft to power an implement or cutter blade located some distance from the gear wheel axle which would be used to power the ground engaging drive wheels.

For some applications it may be desirable to allow the worm gearbox casing 34 to pivot about the longitudinal axis of the input gearbox cross-shaft 28 independent of the chassis in which the gearbox cross-shaft is contained.

The gear wheel axle 16 would be moveably suspended in an arc about the input drive gearbox cross-shaft 28 axis, for example, to form a suspension arm providing drive via gear wheel axle 16 to a ground engaging wheel or wheels. The input gearbox cross-shaft 28 and the gear wheel axle 16 can also be housed in separate casings. This arrangement would facilitate, for example, the worm gearbox casing 34 to move or swivel about gear wheel axle 16 independently of the input drive gearbox cross-shaft 28 and the chassis in which the said gearbox cross-shaft is contained.

In such cases the worm gear shaft 10 pivot axis or point would be external of the said worm gearbox casing The following description and referenced illustrations relate to an extended worm arm arrangement in accordance with the present invention. The worm gear shaft 10 tilt axis is external to the worm gearbox casing An application described below demonstrates the advantages of such an arrangement.

This mechanism provides a positive drive engagement and disengagement means for slow turning high torque drives such as a ground engaging drive axles for pedestrian operated ground working machines such as turf cutters, garden cultivators or grass cutting machinery. The aforementioned mechanism provides a driving means for the ground engaging wheels and an auxiliary driving means for cultivator tines or cutter blades provided on the ground working machine.

The problem for such applications is that the power source is generally provided by an engine or motor having an output shaft speed in excess of rpm. The drive train which couples this power source to the drive axle for a typical ground engaging application such as a wheel axle must reduce the speed to around 50 rpm.

For most applications of this nature it is desirable that the drive train is compact and incorporates a means of disengaging the drive, for example, to enable the operator to wheel the machine unrestrictedly without any resistance or drag from the speed reduction drive train or disengaging means.

Clutches are readily available to disengage the driving means from the ground engaging application such as centrifugal, disc or loose belt clutches. These clutches are best suited to high speed low torque applications and as such are usually incorporated at the engine or power source shaft leaving the ground engaging axle connected to the speed reduction drive train.

This creates drag or resistance and therefore free-wheeling is impaired. High torque clutches are available which would be suitable for incorporating into a wheel axle such as a dog-clutch or plunger-pin drive; these will cope with the high torque requirements and provide unrestricted free wheeling when disengaged but they have other limitations.

For example, they tend to be difficult to engage and disengage especially under load and they offer no means of speed reduction. The mechanism described as follows addresses all of the aforementioned problems and provides a positive high torque engagement, zero drag disengagement and limitless speed reductions eliminating the need for any form of reduction drive train.

The worm gear shaft 10 is housed within an extended worm arm 12 which is rigidly attached by extended worm arm flange 37 at its uppermost end to the said right angle bevel gearbox The right angle gearbox 13 is free to pivot about its axis on gearbox cross-shaft 28 which is supported at either side by gearbox cross-shaft bearing 27 on which the gearbox cross-shaft rotates.

Bearing 27 is located and supported by a main chassis which, for clarity, is not shown in the Figures. Gear wheel axle 16 rotates on wheel axle bearing 29 which is housed within the worm gearbox casing The worm gearbox casing 34 can be firmly fixed or pivotally attached to the main chassis.

The worm gear shaft 10 is connected to and is driven by the gearbox right angle shaft 33 and is supported at its lower end by radial thrust bearing Radial thrust bearing 26 is provided at the lowermost end of extended worm arm 12 and provides radial and linear stability to the lower end of the worm gear shaft. The pivoting action of the right angle gearbox 13 enables worm gear shaft 10 to engage and disengage with worm gear wheel When worm gear wheel 11 and worm gear shaft 10 are engaged, lateral movement of the extended worm arm 12 relative the worm gear wheel 11 is prevented by lateral support pad 32 one of which is fixed to the extended worm arm 12 on either side and in contact with worm gear wheel Lubrication of the pads 32 as they contact gear wheel 11 is provided by lubrication oil within the gearbox casing Engagement and disengagement is implemented by rotating engagement axle 20 via engagement lever Engagement lobe 21 fixed to the said engagement axle acts like a cam in contact with the end of engagement adjuster screw 22 which is adjustably attached to the said extended worm arm Extended worm arm 12 is pushed at its lowermost portion by the rotation of the said engagement axle and swings in an arc about the axis of gearbox cross-shaft 28 towards the gear wheel axle 16 engaging the worm gear shaft 10 with worm gear wheel The engaged worm gear clearance is set by extending or contracting the engagement adjuster screw Disengagement is actuated by grasping the engagement lever knob 30 and the engagement plunger 31 on an uppermost portion until it clears the recess or cut-out in engagement bracket Engagement lever is then free to pivot downwards as illustrated in FIG.

This allows the extended worm arm 12 to swing away from the worm gear wheel 11 assisted by worm arm spring 19 thereby releasing the gear wheel axle 16 and ground engaging wheel 17 to freely rotate. The engagement bracket 24 pivots on engagement axle 20 and is anchored to the main chassis by an adjustment clamp bolt not shown which is located through fine adjustment slot Fine adjustment of the engaged worm gear clearance can easily be set externally for initial set-up and, to compensate for wear, by slackening the adjustment clamp bolt thereby enabling engagement bracket 24 to slide in an arc along the fine adjustment slot In doing so, engagement bracket is rotated about the longitudinal axis of the engagement axle axis thus altering the position of the engagement lobe 21 and thereby the worm-gear clearance.

The engagement adjuster screw 22 is held in contact with engagement lobe 21 by worm arm spring When the engagement lever 25 is set to the disengaged position as shown in FIG. Right angle bevel gearbox 13 is driven by a suitable power source not shown by input drive belt 15 and input drive pulley 14 which is fixed to the input end of the gearbox cross-shaft Power is transmitted via the right angle bevel gearbox 13 to the worm gear shaft 10 which in turn, when engaged, drives the gear wheel axle A sprocket or pulley not shown can be fixed to the output end of the said gearbox cross-shaft opposite to the input drive pulley to provide an auxiliary drive for implements or attachments such as the cutter blade for a grass or turf cutter machine or the tine shaft for a garden cultivator.

Worm gear wheel 11 and the lower portion of the extended worm arm 12 are enclosed within worm gearbox casing The worm gearbox casing 34 contains a lubricant such as oil or grease to lubricate the moving components within. The extended worm arm 12 protrudes through a cavity opening in the uppermost in use portion of the worm gearbox casing. The cavity opening is sealed by gearbox casing cover Flexible seal 18 is attached at its uppermost end to the extended worm arm 12 and at its lower end to the sealed casing cover 35 thus preventing dirt or dust entering worm gearbox casing

Investigations on the Efficiency of Worm Gear Drives

Worm gears are found in industrial applications, heavy equipment, and even consumer applications. Although their efficiency is relatively low, they can provide very high reduction ratios and, in many cases, are self-locking. Worm gears are constructed of a worm and a gear sometimes referred to as a worm wheel , with non-parallel, non-intersecting shafts oriented 90 degrees to each other. The worm is analogous to a screw with a V-type thread, and the gear is analogous to a spur gear. Like a ball screw , the worm in a worm gear may have a single start or multiple starts — meaning that there are multiple threads, or helicies, on the worm. For a single-start worm, each full turn degrees of the worm advances the gear by one tooth. So a gear with 24 teeth will provide a gear reduction of

Compact style also available. This catalog is a supplement to the standard red Bonfiglioli metric catalogs. When evaluating an application, it is recommended that final selections be reviewed by Bonfiglioli personnel. As this is a supplement, refer to the metric catalogs R4 for more detail in regards to each gearbox and gearmotor. Description Ac [lbs] Calculated thrust load [lbs] Rated thrust load - Adjusting power factor - Service factor - Thermal correction factor - Transmission ratio - Intermittence [Ib-ft2] Load moment of inertia [Ib-ft2] Mass moment of inertia for motor [Ib-ft2] Mass moment of inertia for gearbox - Acceleration factor of masses - Radial load stress factor [lb-in] Brake torque [lb-in] Torque [lb-in] Calculated torque [lb-in] Speed reducer rated torque [lb-in] Torque required [rpm] Speed [hp] Power [hp] Calculated power [hp] Motor rated power. It is calculated according to service factor S.


reduction at input. Worm Gear Boxes Product Spectre. Single stage worm gearboxes. A simple and economical solution for most industrial application. Size 30 -.


Worm Gears Explained

Experimental investigations on different worm gears were conducted on several test rigs, taking into consideration the influence of different gear ratios, worm wheel materials, lubricants, and contact pattern on efficiency and load-carrying capacity. Recommendations for an increase in overall worm gearbox efficiencies are presented. Due to a wide range of properties, worm gears are an indispensable element on the current transmission market. Furthermore, worm gears provide the opportunity of self-locking, respectively self-braking. Despite these benefits, as a result of greater energy awareness, the efficiency of worm gears is in focus.

Worm and Worm Gears sets transfer motion between non-intersecting right angle shafts. They are the most compact small precision gears system available, as well as the quietest and smoothest running. A worm and worm gears set can provide a high reduction ratio in a very small space.

Experimental investigations on different worm gears were conducted on several test rigs, taking into consideration the influence of different gear ratios, worm wheel materials, lubricants, and contact pattern on efficiency and load-carrying capacity. Recommendations for an increase in overall worm gearbox efficiencies are presented.

Worm Gears Explained

A worm drive is a gear arrangement in which a worm which is a gear in the form of a screw meshes with a worm gear which is similar in appearance to a spur gear. The two elements are also called the worm screw and worm wheel. The terminology is often confused by imprecise use of the term worm gear to refer to the worm, the worm gear, or the worm drive as a unit.

Care should be taken when selecting a Worm wheel reduction gearbox for a new application. There are many factors that can affect the service life of the unit. The correct selection must be made to ensure the efficiency of the reducer. Some of these factors including service, load, torque etc. Ratings shown are compiled using standard engineering procedures. Prototype testing of every application is recommended before production. Worm wheel reduction gearboxes are made in many styles and sizes.

Experimental investigations on different worm gears were conducted on several test rigs, taking into consideration the influence of different gear ratios, worm wheel materials, lubricants, and contact pattern on efficiency and load-carrying capacity. Recommendations for an increase in overall worm gearbox efficiencies are presented. Due to a wide range of properties, worm gears are an indispensable element on the current transmission market. Furthermore, worm gears provide the opportunity of self-locking, respectively self-braking. Despite these benefits, as a result of greater energy awareness, the efficiency of worm gears is in focus. Because of high sliding velocities, especially at high gear ratios, gearing losses are a main topic of interest.


Miter Gears. Bevel Gears. Screw Gears. W orm. Gear Pairs. Bevel. Gearboxes. Other. Products. Worms. K W G DL 2 - R1. Hand thread & Number of Starts.


Load Capacity of Worm Gears

Experimental investigations on different worm gears were conducted on several test rigs, taking into consideration the influence of different gear ratios, worm wheel materials, lubricants, and contact pattern on efficiency and load-carrying capacity. Recommendations for an increase in overall worm gearbox efficiencies are presented. Due to a wide range of properties, worm gears are an indispensable element on the current transmission market.

US20110247440A1 - Worm gear clutch mechanism - Google Patents

2 comments

Jasmine H.

They are also the smoothest, quietest form of gearing when properly applied.

REPLY

Rachelle B.

Romeo and juliet play in modern english pdf concepts and comments 4 pdf free download

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