CN106475938A

CN106475938A - The Self adapting fixture of connection support bar

Info

Publication number: CN106475938A
Application number: CN201611170840.8A
Authority: CN
Inventors: 龙云
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-12-16
Filing date: 2016-12-16
Publication date: 2017-03-08
Anticipated expiration: 2036-12-16
Also published as: CN106475938B

Abstract

The invention discloses a kind of Self adapting fixture of connection support bar, the support bar is provided with pin-and-hole to connect the fixture, including：Alignment pin, its are mated with the pin-and-hole；Flat key component, it include the second through hole of flat key and the sheathed alignment pin；Bearing, which passes through the alignment pin and the sleeve of the sheathed support bar is connected with the pin-and-hole, arranges the first keyway mated with the flat key on the outside of which；Rotating disk, which is located at below the bearing, the middle part of its upper end is coaxially connected with the sleeve by clutch shaft bearing, its lower end is provided with the nut mated perpendicular to the screw rod of the sleeve and with the screw rod, the outside of its upper end is arranged circumferentially multiple the second keyways mated with the flat key, and the nut is fixedly connected with the rotating disk；Frame-type component, it include the grip block parallel to the guide rail of the screw rod and perpendicular to the guide rail, and the grip block is connected with the screw rod by the coaxial second bearing in the screw rod.The present invention can be clamped to irregular frame.

Description

The Self adapting fixture of connection support bar

Technical field

The present invention relates to mechanical manufacturing field.It is more particularly related to a kind of self adaptation folder of connection support bar Tool.

Background technology

The clamping of broad sense, particularly relates to the clamping to erose obform body here, should include at least following two Aspect：

On the one hand, it is that special-shaped workpiece to no-fix in support platform carries out clamping, now fixture is located at support platform On, it is common in mechanical processing industry, it is often necessary to which frock clamp carrys out some irregular special-shaped workpieces of clamping, if using biography System fixture such as flat-nose pliers or bench vice etc. carry out clamping, and its clamping is unstable or even cannot clamping；Such as making specific purpose tool is carried out Clamping, also can only the same type of workpiece of the same specification of clamping, such as need the other types of special-shaped workpiece of clamping, it is necessary in addition make Clamping is carried out as instrument, the making of these specific purpose tools necessarily causes narrow application range, and cost is high；Now often will be by behaviour Making hand or robot carries out clamping, and frequent using also causes energy consumption this height of great achievement, and people's clamping apparatus compares intelligence machine because of which Cheap and can also Emergency use, become indispensable instrument the advantages of take up an area little, thus result in using two kinds of fixtures solve clamping with A kind of redundancy issue of workpiece；

On the other hand, it is that the moving platform for not yet positioning is fixed on erose supporter, now fixture is located at On moving platform, during being common in field work, outdoor exploration or being not suitable for artificial clamping etc., often occur with artificial clamping Folder partially, press from both sides askew or clamping unstable, even because distance far from clamping the problems such as, and unartificial clamping then generally requires in addition making One intelligent grasping system mated with moving platform size, its high cost, difficulty are big.

Content of the invention

It is an object of the invention at least the above is solved, and provide the advantage that at least will be described later.

It is a still further object of the present invention to provide one kind has been taken into account artificial clamping and electronic clamping two ways, disclosure satisfy that Irregular frame is clamped and can be set to close self adaptation state when rule clamping is met with dividing and rule and not advise The Self adapting fixture of the connection support bar for being set to open self adaptation state when then clamping, its belong to a kind of and can achieve that " machine is many With ", beneficial to simplify grasping system design device.

In order to realize according to object of the present invention and further advantage, there is provided a kind of self adaptation folder of connection support bar Tool, perpendicular to caught object by contained side frame, the support bar is provided with pin near described one end by contained side frame to the support bar Hole, the front by contained side frame are provided with least two support bars being mutually permanently connected, any one of support Bar is connected with the Self adapting fixture by the pin-and-hole of its own, and the Self adapting fixture is described by contained side for clamping Frame, the Self adapting fixture include infrastructure component, and the infrastructure component includes：

Alignment pin, its are mated with the pin-and-hole；And

Flat key component, it include the second through hole of flat key and the sheathed alignment pin；And

Bearing, which passes through the alignment pin and the sleeve of the sheathed support bar is connected with the pin-and-hole, arranges on the outside of which The first keyway mated with the flat key, coarse first the rubbing for frictional drive of coaxially connected one its lateral surface of the sleeve Wipe ring；And

Rotating disk, its are located at the lower section of the bearing, and the middle part of its upper end is coaxially connected with the sleeve by clutch shaft bearing, Its lower end is provided with the nut mated perpendicular to the screw rod of the sleeve and with the screw rod, and the outside of its upper end is arranged circumferentially multiple The second keyway mated with the flat key, the nut are fixedly connected with the rotating disk；And

Frame-type component, its are located at the lower section of the rotating disk, and which is included parallel to the guide rail of the screw rod and perpendicular to described Guide rail and for clamping the grip block by contained side frame, the grip block is by coaxial in second bearing and the institute of the screw rod Screw rod connection is stated, the frame-type component is slidably connected with the rotating disk by the guide rail.

Preferably, rope can be carried by one between Self adapting fixture described in any two or connecting post connects, described The upper end of seat is provided with one for carrying rope or connecting post work spacing ring spacing up and down to described.

Preferably, the top of first keyway is provided with the position of berthing for the flat key that berths.

Preferably, also include to be arranged on the infrastructure component, for replacing the separable modules for manually being clamped, institute Stating separable modules includes：

First gear, it is separably coaxial with one end away from the second bearing of the screw rod which passes through the first bearing pin Connection；And

Piezoelectric transducer, its are folded between second bearing and the grip block, and which is used for measuring the grip block and is subject to Extraneous produced reaction force of conflicting；And

Electronic portion, it include the second motor to the first motor of the first drag ring transmission and to first gear transmission And the motor support base of carrying first motor and second motor, the middle part of the motor support base arranges and wears described turning The fourth hole of disk, the motor support base are separably attached with the rotating disk by the second bearing pin, set on the motor support base Its measurement direction is put parallel to the length direction of the screw rod, for the center of the rotating disk being measured with described by contained side frame The distance measuring sensor of distance between nearest face；

Wherein, first motor is connected with the distance measuring sensor, and second motor is connected with the piezoelectric transducer Connect.

Preferably, second motor is by driving a spool gear and the first gear engaged transmission.

Preferably, first motor is driven with first drag ring by driving one second drag ring, and described second The lateral surface of drag ring is coarse for frictional drive.

Preferably, first motor is hinged on described by two symmetrically arranged 3rd bearing pins and the motor support base The lower section of the first motor, the 3rd bearing pin is perpendicular to the ring heart of first drag ring and connecting with the heart for the ring heart of the second drag ring Line, the top of first motor arrange one parallel to the line of centres spring, the spring has precompression and its two ends Conflict respectively first motor and the motor support base, the stopper slot of a sheathed spring is set on the bearing.

The present invention at least includes following beneficial effect：This device is using the flat key component pair that can be rotated along itself through hole and institute State the coaxially connected rotating disk of support bar implement radially spacing or do not implement spacing, correspondingly so that being arranged on the rotating disk and logical The grip block for crossing screw rod regulation chucking power can be implemented conventional clamping, also can be supported with the external world in clamping process with fixed-direction Adaptively rotate when tactile to the clamping direction for making clamp position gradually stable, irregular frame is clamped, naturally may be used Clamped by increasing the support bar to suitable number and installing this device for each described support bar, this device also by Separably arranging includes：For driving the rotating disk and driving the electronic portion of the screw rod, be fixedly connected on the electronic portion On the center for measuring the rotating disk and the nearest face by contained side frame between the distance measuring sensor of distance and be used for Measure the piezoelectric transducer that the grip block is subject to the reaction force produced by extraneous conflict, etc. for replacing manually being pressed from both sides The separable modules that holds, and then so that this device manually can be carried out clamping and can be clamped by electric drive, make device Expansion and practicality are greatly increased.

Part is embodied by the further advantage, target of the present invention and feature by description below, and part will also be by this The research of invention and practice and be understood by the person skilled in the art.

Description of the drawings

Fig. 1 is the explosive view of heretofore described infrastructure component；

Fig. 2 is the structural representation of heretofore described infrastructure component；

The schematic diagram clamped to quadrangle frame for the present invention by Fig. 3；

The schematic diagram clamped to irregular frame for the present invention by Fig. 4；

Fig. 5 is the structural representation of heretofore described separable modules.

Specific embodiment

The present invention is described in further detail below in conjunction with the accompanying drawings, to make those skilled in the art with reference to specification text Word can be implemented according to this.

It should be noted that experimental technique described in following embodiments, if no special instructions, is conventional method, institute Reagent and material is stated, if no special instructions, is all commercially obtained；In describing the invention, term " horizontal ", " vertical To ", " on ", D score, "front", "rear", "left", "right", " vertical ", " level ", " top ", " bottom ", " interior ", the instruction such as " outward " side Position or position relationship are based on orientation shown in the drawings or position relationship, are for only for ease of the description present invention and simplify description, Be not indicate or imply the device of indication or element must with specific orientation, with specific azimuth configuration and operation, because This is not considered as limiting the invention.

In one embodiment, as shown in figure 1, the present invention provides a kind of Self adapting fixture of connection support bar, described Perpendicular to caught object by contained side frame 1002, the support bar is provided with a pin near described one end by contained side frame to strut 1001 Hole, the front by contained side frame are provided with least two support bars being mutually permanently connected, any one of support Bar is connected with the Self adapting fixture by the pin-and-hole of its own, and the Self adapting fixture is described by contained side for clamping Frame.Wherein, the Self adapting fixture includes infrastructure component, and the infrastructure component includes：

Alignment pin 1, its are mated with the pin-and-hole, and the Self adapting fixture is connected with the support bar by the alignment pin Connect；And

Flat key component 3, its upper end are provided with the second through hole 301 of the sheathed alignment pin, and its lower end is set to flat key 302, institute Stating flat key can be along the axial-rotation of second through hole；And

Bearing 4, which passes through the alignment pin and the sleeve 2 of the sheathed support bar is connected with the pin-and-hole, sets in the middle part of which There is the third through-hole 401 of the sheathed sleeve, the first keyway 402 mated with the flat key is set on the outside of which, the sleeve Upper end is provided with the first through hole 201 that mates with the alignment pin, and coaxially connected one its lateral surface of the sleeve is coarse for rubbing The first drag ring 403 of transmission is wiped, the top of first keyway is provided with the position 404 of berthing for the flat key that berths；And

Rotating disk 5, its are located at the lower section of the bearing, and the middle part of its upper end is coaxially connected with the sleeve by clutch shaft bearing 6 Connect, its lower end is provided with the nut 8 mated perpendicular to the screw rod 7 of the sleeve and with the screw rod, the outside ring of its upper end sets Four the second keyways 501 that can mate are put with the flat key, and the outer ring of the nut is fixedly connected with the rotating disk, described The inner ring of one bearing is fixedly connected with the sleeve, and the outer ring of the clutch shaft bearing is fixedly connected with the rotating disk；And

Frame-type component 9, its are located at the lower section of the rotating disk, and which includes two parallel to guide rails 10 of the screw rod and vertical In the guide rail and for clamping the grip block 11 by contained side frame, the inner side of the grip block is by coaxial in the screw rod Second bearing 12 be connected with the screw rod, the frame-type component is slidably connected with the rotating disk by the guide rail.

The workflow of the present embodiment is as follows：The alignment pin wear simultaneously the pin-and-hole, the sleeve, the bearing and On the one hand the flat key component, causes the bearing to be fixedly connected the support bar, and on the other hand, the rotating disk is by described the One bearing is coaxially connected with the sleeve so that the rotating disk can be along the axial-rotation of the sleeve, so as to for the grip block Grip block adjust automatically itself corner is enabled with by the nearest face of contained side frame by mutually conflicting, as realize self adaptation Ground clamping is described to be provided the foundation by contained side frame.

In another embodiment, the alignment pin is detachably connected by screw thread with the bearing.

In another embodiment, the number of the guide rail can be one or more, when the number of the guide rail is 1, institute The cross section for stating guide rail is set to U-shaped, and the middle part of the guide rail overlapped with the screw rod, is so arranged and is effectively enhanced clamping The balance of block；When the number of guide rail is more than 1, multiple guide rails are symmetrically arranged at the both sides of the screw rod.

In another embodiment, the second bearing is set to plane bearing so that second bearing compares other kind of class bearing The bigger reaction force that can be born in clamp position.

In another embodiment, as in Figure 2-4 (wherein, Fig. 2 is the structural representation of the infrastructure component, under Fig. 3 It is the top view clamped by quadrangle frame, is the structural representation clamped by quadrangle frame on Fig. 3, Fig. 4 is left Side is the top view clamped by the housing to irregular frame, is that the inside casing to irregular frame is clamped on the right side of Fig. 4 Top view), the present invention includes two kinds of working methods, and the first is to close self adaptation state, manually rotates the flat key component, makes The flat key 302 while fall into first keyway 402 and second keyway 501 so that the bearing with described turn Disk is constituted and is fixedly connected relation, and manual adjustment screw rod causes the grip block and conflicted by the nearest face of contained side frame, now The rotating disk can not be along itself rotation because being fixed, and this working method belongs to conventional clamping, is generally used for clamping cross section and is Quadrangle by contained side frame；It is for second that self adaptation state is opened, the flat key component is manually rotated, so that the flat key 302 is fallen Enter the position 404 of berthing, due to the flat key the rotating disk is not carried out spacing so that the rotating disk can be along the axle of the sleeve To rotation, now adjusting screw rod causes the grip block and is conflicted by the nearest face of contained side frame, and then causes the clamping Itself corner of block adjust automatically and gradually stable clip position is in, this working method is applicable to automatic capturing clamping side To, clamped cross section for arbitrary shape by contained side frame, the cross section for example triangle, circle, ellipse, rhombus, Irregular shape etc.；

In another embodiment, when the clamping direction between the grip block and the nearest face by contained side frame and position relationship When substantially meeting the clamping of regular frame【In fact, irregularly shaped part and rectangular shaped portions all may be present in same quilt In contained side frame】, preferably this device is set off self adaptation state, can not substantially carry out when closing self adaptation state is set to During stable holding, when especially irregularly clamping, then self adaptation state is set on, by the technology hand that so divides and rule Section causes to clamp in hgher efficiency, stability more preferably.

In another embodiment, rope 1301 or connecting post can be carried by one between Self adapting fixture described in any two 1302 connections, the upper end of the bearing are provided with one for carrying rope or connecting post work spacing ring spacing up and down to described 405, the rope or the effect of the connecting post of carrying is effectively to offset the anti-work that grip block is subject to produce when being conflicted by contained side frame Firmly so that support bar is unlikely under clamp position because direction causes described perpendicular to the reaction force of the support bar Strut flexural deformation, effectively enhances the stability of clamping.

In another embodiment, for the clamping of any irregular frame, either clamp in housing or clamping Frame, can be achieved by increasing the support bar to suitable number and installing this device for each described support bar automatically The self adaptation in centering clamping direction is clamped, and particularly avoids the problems such as appearance folder is inclined, it is askew to press from both sides or clamps unstable, the letter of this apparatus structure Single, clamping is convenient, and effect is good.

In another embodiment, present invention additionally comprises be arranged on the infrastructure component, for replacing manually being pressed from both sides The separable modules that holds, as shown in figure 5, on the right side of in figure for the present invention structural representation, be described separable group on the left of in figure The structural representation of part, the separable modules include：

First gear 15, its pass through the one end away from the second bearing of the first bearing pin 16 separably with the screw rod Coaxially connected；And

Piezoelectric transducer 14, its are folded between second bearing and the grip block, and which is used for measuring the grip block receives To the reaction force produced by extraneous conflict；And

Electronic portion, it include the first motor 17 being driven to the first drag ring 403 and to first gear transmission the Two motors 18 and the motor support base 19 of carrying first motor and second motor, the middle part of the motor support base are arranged The fourth hole 1901 of the rotating disk is worn, the motor support base is separably attached with the rotating disk by the second bearing pin 20, One its measurement direction is set on the motor support base parallel to the length direction of the screw rod, for measuring the center of the rotating disk The distance measuring sensor 21 of distance between the nearest face by contained side frame, the distance measuring sensor can be ultrasonic ranging mould Block；

Wherein, first motor is connected with the distance measuring sensor, and second motor is connected with the piezoelectric transducer Connect, by driving a spool gear 22 and the first gear engaged transmission, first motor is by driving for second motor One second drag ring 23 is driven with first drag ring, and the lateral surface of second drag ring is coarse for frictional drive；

The motion mode of the present embodiment, including three steps：

This fixture is set on self adaptation state by the first step first, i.e., so that the flat key 302 falls into described berthing Position 404, due to the flat key the rotating disk is not carried out spacing so that the rotating disk can along the axial-rotation of the sleeve,

Second step, controls first motor to be driven with first drag ring 403 by driving the second drag ring 23, from And the rotating disk is caused along the axial-rotation of the support bar, the motor support base also follows the rotating disk to do identical fortune Dynamic, on the one hand, can be measured between the center of the rotating disk and the nearest face by contained side frame by the distance measuring sensor Distance, you can with by 360 degree rotating the distance measuring sensor and record the distance, after rotating a circle by acquisition many Minimum range in individual distance, continues control the first motor rotation, until the distance of distance measuring sensor measurement is approximately equal to During the minimum range, stop the rotation of the first motor【When the motor that the first motor is controllably angle displacement, such as servo electricity Machine, steering wheel, stepper motor etc., can one side obtain described apart from while record the corresponding angular displacement, so as to work as After rotating a circle, the first motor of control rotates angular displacement corresponding to the minimum range, stops the rotation of the first motor】,

3rd step, controls the second motor rotation, by driving spool gear 22 and 15 engaged transmission of the first gear, So that the screw rod is on the one hand along itself axial-rotation, on the other hand the screw rod is while sliding axially along itself, this Shi Suoshu first gear also follow the screw rod do described slide axially, as the length of the spool gear compares first tooth The length of wheel is longer so that the first gear still keeps engaged transmission with the spool gear, so as to drive the screw rod according to So slide axially along itself, and then promote the grip block 11 to implement holding action towards being frameed shift to move by contained side, when the folder Hold block to be conflicted by contained side frame by described, the piezoelectric transducer 14 is the measurable produced reaction force of conflicting, When the reaction force reaches set force value, represent that clamping work is completed, stop second motor and rotate, that is, achieve and pass through Electric drive replaces the purpose for manually being clamped；Therefore it is suitable for replacing manually being clamped, nobody is especially suitable for Operation when participating in the cintest, installation are connected in robot, implement the occasion of long-range self adaptation clamping.

In another embodiment, first motor is propped up with the motor by two symmetrically arranged 3rd bearing pins 24 Seat is hinged on the lower section of first motor, and the 3rd bearing pin is perpendicular to ring heart and second drag ring of first drag ring Ring heart line of centres, the top of first motor arrange one parallel to the line of centres spring 25, the spring has Precompression and its two ends are conflicted first motor and the motor support base respectively, arrange a sheathed spring on the bearing Stopper slot 1902；

In terms of the working method of the present embodiment includes following three：On the one hand, described second is caused to rub by the spring Wipe between ring and first drag ring and good contact is remained when dependence frictional force is driven, effectively prevent Transmission slip, on the other hand, when because the extraneous grip block of conflicting causes the rotating disk to bear in self adaptation clamping process When torque is more than the mutual frictional resistance of two drag rings, second drag ring can be flexibly with first drag ring Skid so that rotating disk still can be rotated to stable clamping direction by external force, and the third aspect is because service wear is overproof, described Second drag ring and first drag ring will all occur unpredictalbe deformation, and such setting obviously automatically can be caused Second drag ring and first drag ring remain contact, so as to be effectively improved the stability of transmission.

This device is adopted can be implemented along the flat key component pair of itself through hole rotation rotating disk coaxially connected with the support bar Radially spacing or do not implement spacing, correspondingly so that the grip block for being arranged on the rotating disk and chucking power being adjusted by screw rod both Can with fixed-direction implement conventional clamping, also can in clamping process with extraneous conflict when adaptively rotate to making clamping shape The gradually stable clamping direction of state, clamps for irregular frame, naturally can be by increasing the support bar to suitable number Mesh is simultaneously installed this device for each described support bar and is clamped, and this device includes also by separably arranging：For driving The electronic portion of the rotating disk and the driving screw rod, the center for measuring the rotating disk being fixedly connected in the electronic portion The distance measuring sensor of distance and conflicted by the external world for measuring the grip block between the nearest face by contained side frame The piezoelectric transducer of produced reaction force, etc. for replacing the separable modules for manually being clamped, and then cause this Device manually can be carried out clamping and can be clamped by electric drive, greatly increase the expansion of device and practicality.To the greatest extent Pipe embodiment of the present invention is disclosed as above, but which is not restricted in specification and embodiment listed utilization, and it is complete Various suitable the field of the invention can be applied to entirely, for those skilled in the art, be easily achieved in addition Modification, therefore under the universal limited without departing substantially from claim and equivalency range, the present invention is not limited to specifically Details and shown here as with description legend.

Claims

1. a kind of Self adapting fixture of connection support bar, the support bar is perpendicular to caught object by contained side frame, the support Bar is provided with pin-and-hole near described one end by contained side frame, and the front by contained side frame is provided with least two and is mutually permanently connected The support bar, any one of support bar is connected with the Self adapting fixture by the pin-and-hole of its own, described Self adapting fixture is described by contained side frame for clamping, it is characterised in that the Self adapting fixture includes infrastructure component, the basis Component includes：

Alignment pin, its are mated with the pin-and-hole；And

Bearing, which passes through the alignment pin and the sleeve of the sheathed support bar is connected with the pin-and-hole, arranges and institute on the outside of which The first keyway of flat key coupling is stated, coarse the first friction for frictional drive of coaxially connected one its lateral surface of the sleeve Ring；And

Rotating disk, its are located at the lower section of the bearing, and the middle part of its upper end is coaxially connected with the sleeve by clutch shaft bearing, under which End is provided with the nut mated perpendicular to the screw rod of the sleeve and with the screw rod, and the outside of its upper end is arranged circumferentially multiple and institute The second keyway of flat key coupling is stated, the nut is fixedly connected with the rotating disk；And

Frame-type component, its are located at the lower section of the rotating disk, and which is included parallel to the guide rail of the screw rod and perpendicular to the guide rail And for clamping the grip block by contained side frame, the grip block is by coaxial in second bearing and the spiral shell of the screw rod Bar connects, and the frame-type component is slidably connected with the rotating disk by the guide rail.

2. the Self adapting fixture of connection support bar as claimed in claim 1, permissible between Self adapting fixture described in any two Rope or connecting post connection are carried by one, it is characterised in that the upper end of the bearing is provided with one for the carrying rope or institute State connecting post and make spacing ring spacing up and down.

3. the Self adapting fixture of connection support bar as claimed in claim 1, it is characterised in that the top of first keyway sets Have the position of berthing that flat key is stated for anchorage.

4. the Self adapting fixture of connection support bar as claimed in claim 1, it is characterised in that also include to be arranged on the basis On component, for replacing the separable modules for manually being clamped, the separable modules include：

First gear, its are passed through the first bearing pin and are separably coaxially connected with one end away from the second bearing of the screw rod Connect；And

Piezoelectric transducer, its are folded between second bearing and the grip block, and which is used for measuring the grip block by the external world Reaction force produced by conflicting；And

Electronic portion, it include to the first drag ring transmission the first motor and to the first gear transmission the second motor and The motor support base of first motor and second motor is carried, the middle part of the motor support base arranges and wears the rotating disk Fourth hole, the motor support base are separably attached with the rotating disk by the second bearing pin, arrange one on the motor support base Its measurement direction parallel to the screw rod length direction, for measure the rotating disk center with described by the nearest of contained side frame The distance measuring sensor of distance between face；

Wherein, first motor is connected with the distance measuring sensor, and second motor is connected with the piezoelectric transducer.

5. the Self adapting fixture of connection support bar as claimed in claim 4, it is characterised in that second motor is by driving One spool gear and the first gear engaged transmission.

6. the Self adapting fixture of connection support bar as claimed in claim 4, it is characterised in that first motor is by driving One second drag ring is driven with first drag ring, and the lateral surface of second drag ring is coarse for frictional drive.

7. the Self adapting fixture of connection support bar as claimed in claim 4, it is characterised in that first motor passes through two Symmetrically arranged 3rd bearing pin is hinged on the lower section of first motor with the motor support base, and the 3rd bearing pin is perpendicular to institute The line of centres of the ring heart of the first drag ring and the ring heart of the second drag ring is stated, the top of first motor arranges one parallel to institute The spring of line of centres is stated, the spring has a precompression and its two ends is conflicted respectively first motor and the motor support base, The stopper slot of the one sheathed spring is set on the bearing.