CA1149197A

CA1149197A - Gearbox

Info

Publication number: CA1149197A
Application number: CA000375728A
Authority: CA
Inventors: Leslie Baines; Eric Bottomley
Original assignee: Pitcraft Summit Ltd
Current assignee: Pitcraft Summit Ltd
Priority date: 1980-04-18
Filing date: 1981-04-16
Publication date: 1983-07-05
Also published as: CA1138679A; ZA812345B; AU6917781A; ZA812422B; AU539436B2; AU6937781A; DE3114978A1

Abstract

ABSTRACT

"GEARBOX"

A gearbox 1 comprises a housing 2 containing a reduction stage 18 comprising a first gear 19 rotatable about a axis 20 and in mesh with a second gear 21 rotatable about parallel axis 22, the first gear 19 being mounted in a carrier 23 pivotable about the axis 22 of the second gear 21 and constrained by a torque sensing device 26 connected between the carrier 23 and the housing 2.

Description

L9t-~

GEARBOX
This invention relates to a gearbox, of the single speed or change speed type.
Gearboxes are often employed in service conditions S where loading;1s erratic and on occasion in excess of design limits, e.g. when driving an underground mineral carrying convenor. Furthermore, if such a convey~r is of the scraper chain type and located along a mineral, e.g. coal face, it is not uncommon for the conveyor to~jam for one reason or another, possibly resulting in damage to the gearbox and/or any intermediate transmission between the gearbox and the conveyor.
The invention pertains to a gearbox which includes a housing, a main reduction stage contained within the housing, and a preliminary reduction stage preceding~the~main reductlon stage and also contained within the housing. The prelimlnary reductlon stage comprises an input shaft rotatable about an axis ; and connectable to a prime mover, a gear carried by the lnput shaft, a lay shaft, a gear mounted in bearings on the lay shaft and constantly~ln mesh w1th the input shaft gear, and a clutch to drivably connect or disconnect the lay shaft gear to the lay shaft, the latter being rotatable about an axis spaced from, a~d parallel to, the~input shaft;axis. ~ flexible gear type coupli~g i~ provided at one termlnal end of the lay shaft to n~@~ ~h~ la~ shaft to the main reduction stage. The main .

~ .

-L97~ 2 reduction stage comprises a first gear rotatable about an axis, a second gear xotatable about a parallel axis and in mesh with the first gear, and a carrier pivotable about the axis of the second gear, the first gear being mounted in the carrier with a torque sensing device connected between the carrier and the housing.

When drive is applied to the gearbox and one of the clutches is engaged so as to transmit the drive through the - gearbox, the reaction torque on the carrier is continuously monitored by the torque sensing device, which provides for overload protection, e.g. by activating a switch controlling current to the electric motor, and hence obviating damage to the gearbox etc., upon a predetermined torque being exceeded.

The gearbox may comprise basically a preliminary reduction stage preceding the first mentioned reduction stage.
In detail, the gearbox may comprise an input shaft connectable to a prime mover and carrying a gear constantly in mesh with a gear mounted in bearings on a lay shaft, a clutch to drivahly connect or disconnect the gear to the lay shaft, the latter being rotatable about an axis spaced from, and parallel to, the axis of the input shaft, terminating in a flexible gear type coupling to the first mentioned reduction stage. In a change speed form, the gearbox may be provided with a connecting gear fixed to the lay shaft and permanently in mesh with a "

9~97 ; ~ :
gear mounted in bearings on the input - shaft, with a further clutch to drlvably interconnect or dlsconnect~the connecting gear to the input~shaft.
P~eferably, the carrier also carries the second gear as well as the first gear of the first mentioned reduction stage. The input shaft may incorporate~ an internally splined or geared socket~to receive a male, externally splined spigot of the prime mover. ~ ~
If still further speed reduction~is ~ required, the output shaft of the first - ~ mentioned r~eduction stage may be connected~
to~the input shaft of a further reduction stage. The requirements for particular speed reductions will of course depend on ;
whether the gearbox is intended for transmitting ; power to a conveyor, where further speed ~ reduction would be required.
In detail, the torque sensing device may be connected electrically to an electric motor constltuting the prime mover, to switch off the motor upon a predetermined torque being exceeded.
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~9lg7 : ~ - 4 -The invention will now be ~described in greater detailj by way of :example, with reference to the accompanying drawings, in~whiah:-: Figure 1 is:an axial sectional , ~ view through a ~speed change gearbox in .
accordance with the invention;
Figure 2 is a section Qn the line II-II of Figure 1.
In the drawings, the gearbox, indicated at l, comprises a housing 2 rotatably supporting an input shaft 3 rotatable about an axis 4, and having a female, internally splined socket 5 ta 15. receive a male, externally splined spigot 6 from an electric motor ~not shown) to which :
the gearbox 1 is bolted. ~he input shaft 3 :
has external teeth 7 constantly in mesh with . a gear 8 mounted in bearings 9 on a lay shaft lO~rotatablè about an axis 11 spaced from, and para~llel to, the axis 4. The gear 8 is connected by bolts 12 to first e`lements 13 of .
a hydraulically operable alutah~14 with seaond ele`ments 15 aarried by the lay shaft lO, the 25 . la`tter terminàting in a flexible gear type:
::

-: .. ' ' : ,;... - ~ ' :: :
.

~49197 ' : , coupling compri-sing a female, internally splined socket 16 to receive a male, externally splined splgot 17 of a final reduction stage 18.
The final redaction stage 18 comprises a first gear 19 drivable by the spigot 17 about an axis~20, and in mesh with a secon'd gear~21'rotatable about à
Parallel 'axi5 22, both gears being mounted within a pivotable carrier 23. The carrier 23 is pivotable about the~axis 22 by being mounted for pivotal movement about bearing faces 24 and shoulders 25 of the housing 2.
However, pivotal movement of the carrier 23 is cons~rained by a torque senslng device 26 connected between the carrier 23 and the housing ¦ ~,

2, wit~ the torque sensing device electrically I ;' connected to the electric motor. Thus, pivotal movement of the carrier 23 about axis ~ 22 is constrained by the torque sensing device :
26 and henca the torque sensing device 26 can be pre-set~to allow a predetermined strain to occur and hence a pr~edetermined torque le'vel to be~
attained which level, when exceeded, e.g. by an unusual load belng~imposed on the conveyor or by -9~

the conveyor becoming jammed, triggers the torque sensing device 26 to switch off the electric motor to avoid unnecessary damage to the electric motor, the gearbox 1, and the subsequent transmission -to the conveyor.
The input shaft 3 also carries ~
first elements 27 of a further hydraulicalIy 1.
operable clutch 28, with second elements 29 ~ .
bolted to a gear 3O, mounted in bearings 31 on the input shaft 3. The gear 30 is constantly in mesh with a connecting gear 32 fixed to the lay shaft lO. Thus, selective operation of a clutch 14 or 28 drives the : 15 lay shaft lO respectively either through the gear 8, as a preliminary reduction stage, or - through the gear 32, as an alternative preliminary reduction stage, while oil for the~clutches is provided by a pump 33 driven . I
by a gear 34 permanently in mesh with the teeth 7 of the input shaft 3.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A gearbox comprising a housing; a main reduction stage contained within said housing; a preliminary reduction stage preceding said main reduction stage and also contained within said housing, said preliminary reduction stage comprising an input shaft rotatable about an axis and connectable to a prime mover, a gear carried by said input shaft, a lay shaft, a gear mounted in bearings on said lay shaft and constantly in mesh with said input shaft gear, a clutch to drivably connect or disconnect said lay shaft gear to said lay shaft, the latter being rotatable about an axis spaced from, and parallel to, said input shaft axis, and a flexible gear type coupling provided at one terminal end of said lay shaft to connect said lay shaft to said main reduction stage; said main reduction stage comprising a first gear rotatable about an axis, a second gear rotatable about a parallel axis and in mesh with said first gear, a carrier pivotable about said axis of said second gear, said first gear being mounted in said carrier, and a torque sensing device connected between said carrier and said housing.

2. A gearbox as claimed in Claim 1, in a speed change form, comprising a connecting gear fixed to said lay shaft, a gear mounted in bearings on said input Shaft and permanently in mesh with said connecting gear, and a further clutch to drivably interconnect or disconnect said connecting gear to said input shaft.

3. A gearbox as claimed in Claim 1, wherein said carrier also carries said second gear as well as said first gear of said main reduction stage.

4. A gearbox as claimed in Claim 1, 2 or 3, wherein said input shaft incorporates an internally splined socket to receive a male, externally splined spigot of the prime mover.

5. A gearbox as claimed in Claim 1, wherein said clutches are hydraulically operable.

6. A gearbox as claimed in Claim 5, wherein a pump driven by a gear permanently in mesh with said gear of said input shaft provides hydraulic fluid for said clutches.