DD157727A5 - Schwingungsdaempfer - Google Patents

Abstract

The invention aims to provide a Schwingungsdaempfers for suppressing the vibrations on handles of vibrating machines, such. Motor chain saws, whereby the harmful effects of vibration can be kept away from the operator. The Schwingungsdaempfer consists of a specially shaped spring unit between handle and swinging body. The spring is wound several times Tonnenfoermig and held with their narrower turns on a Traegerelement the vibrating body and with the other turns on the handle shift.

Description

Berlin, July 10, 1981.

ζ 1 *} - 1 - AP F16F / 228 663/2 U vl &. 59 027/27

Vibration damper ·

Field of application of the invention

The invention relates to a vibration damper and more particularly to a vibration damper for a handle, a machine, a vehicle or the like which constitutes a source of vibration, for example a chainsaw or a motorcycle.

Charakj _n er ^

The support member for the manual control of a chain saw, a motorcycle or other vibration generating body is usually provided with a cylindrical handle or the like for direct handling by the operator. At the same time, the vibrations from the source are transmitted immediately to the support member and the handle, causing the user's hand or hands to vibrate, and often so much that health is compromised. "For example, it is well known that the chainsaw oscillates during the cutting process Cause of Reynaud's disease are already numerous attempts have been made. to isolate the vibrations of such saws, motorcycles and other similar sources. protect human body, zn * So far, however, has not yet achieved a satisfactory solution.

It is therefore an object of the present invention to provide a vibration damper for the handling of chainsaws, motorcycles and other 'oscillatory' mechanical

^ η '' ^ '· η ^{59 Ο27 / 27}

To create bodies to protect Mutzer from Reynaud's disease and other harmful health effects *

It is an object of the invention to provide a vibration damper consisting of a spring unit of a special construction which is connected by a handle to a vibrating mechanical body, in which the vibrations which are otherwise caused by the grip of the me- · be transmitted to the user, essentially attenuated or absorbed

According to the invention this object is achieved in that the 8Ji a vibration body for handling provided, z, B. formed as an arm carrier arm welists a cylindrical handle welists in which a vibration-damping spring is provided, 'a number of small and large winding' and between the support member and the handle, each small winding part being held by the support element and each large boulder part by the inner surface of the handle, and the vibration transmitted from the vibration body to the support member being absorbable by the vibration damping spring. In an advantageous embodiment of the invention, it is provided that the cylindrical handle consists of an outer sleeve of rubber or other elastic material which is connected to an inner cylinder of metal, and that the vibration-damping spring is divided into a Vielζaiii of barrel-shaped units, which in an axie, len Row 'are arranged, wherein the two outer ends of the spring geha lts formed by flanges at both ends of the outer sleeve.

59 027/27

In addition, however, it is also possible that the cylindrical handle consists of a single metallic cylinder * and the two outer ends of the vibration-damping spring are held by splashing attached to both ends of the metallic cylinder.

The vibration damper according to the invention can also be designed so that the cylindrical handle consists of an inner and an outer metallic cylinder, wherein the two cylinders are held at a suitable distance from each other, and that the two outer ends of the vibration-damping spring in this space from at both ends of inner metallic cylinder arranged splashing are held _c

In the meaning of the invention, furthermore, when the cylindrical handle is made of an inner metallic cylinder and an outer cylinder made of rubber or other elastic material which are at a suitable distance from each other, the inner metallic cylinder has cylindrical extensions at both ends Head screws are attached to the support member, and also provided at both ends with splashing through which the two outer bands of the vibration-damping spring had been dom in room. It is also advantageous in this context, when the outer cylinder made of elastic Eaterial connected to a metal cylinder becomes.

It is also useful if the cylindrical handle is made of a rubber cylinder, synthetic resin or other elastic Haterial and is provided on the outer periphery with a plurality of non-lubricious circumferential annular surfaces' Advantageously, it is also possible that the cylindrical handle a rubber

Ί Ί '

59 027/27

Cylinder "is made of sponge rubber at the outer periphery of a plurality of slidable circumferential ribs 5, thus facilitating the retention of the same as in the aforementioned embodiment of the damper.

A further advantageous embodiment of the invention is that the cylindrical handle consists of a rubber cylinder having a plurality of annular stiffening ribs which are located on the inner periphery wherein the vibration-damping springs with their elevations in between the annular recesses formed by the-Verteilungsrippen are kept *

It is expedient, furthermore, that the vibration-damping spring is made of a plurality of in-plane one behind the other angeordneter5 at right angles to the-2'rägerschse stationary helical spring units _$ it is also low in this context, call both the inner and the outer Iin. The spring-damping spring can also advantageously consist of a variety of Flachiiiaterial in the same?: '· level and at right angles to the spring of annular grooves, which are mounted in the support element and the inner metallic cylinder of the handle A further advantageous feature of the invention is that the cylindrical handle is a thick-walled blanket cylinder having hollow portions which are gradually reduced in diameter rearwardly from the central portion and connected to a reinforcing metallic cylinder "

• 59 027/27

The cylindrical handle may also be a straight blanket cylinder connected to a reinforcing metallic cylinder, the intended vibration-damping spring being composed of a plurality of barrel-shaped units which reduce from the two ends of the spring to the central portion successively in diameter are.

Preferably, the vibration damping spring consists of a plurality of spring units, wherein the inner and the outer ends of the spring unit are double wound, resulting in a secure attachment of the spring to the support member.

A further advantageous form of the invention is that the cylindrical handle consists of a metallic cylinder of small diameter, the ends of which are widened, wherein the part of the cylinder with the. smaller diameter a cylinder of rubber or other elastic material · picks up and inside the cylinder. recorded units · are held by helical springs in the region of its revaluation in which sleeves fixed to the carrier element are held «.

The invention is explained in more detail below on the basis of exemplary embodiments. '".

Fig. 1: a perspective view of a chain saw with a vibration damper according to the invention;

Fig. 2 is a sectional view of a vibration damper according to the invention; ,

Pig. 3s the picture I-1 after Pig-2; ·

Fig. 4 shows a sectional view of another vibration damper according to the invention;

'Pig' 5ϊ the section H-II of Fig. 4;

Fig. 6 is a sectional view of another embodiment of the invention;

Pigc 7t cut IH-III to Pig. .6;

Fig. 8 is a sectional view of another embodiment; .

Pig 9: the section IV-IV after Pig. S;

Fig. 10 is a sectional view of another embodiment;

Pig. 11: the section V-V to Pig. TO ;.

Pig "12: a sectional view of another embodiment" at play:.

Pig «, 1.3: the section VI-VI after Pig« 12; -

Pig. "Fig. 14 is a sectional view of another embodiment."

Pig ο 15 'the section VH-VII after Pig. 14 *

Pig "16: a chapeau, another example;

59-027 / 27

Γ C OO τ

Pig. 17: the section VlII-VIII after Pig. 16;

Pig. Fig. 18 is a sectional view of a further embodiment;

Fig. 19: the section. IX-IX after Pig. 18;

Pig. FIG. 20 is a sectional view of a fourth embodiment; FIG.

Pig, 21: the cut X-X after Pig. .20 ·;

Pig «22: a sectional view of an additional embodiment;

Pig. 23: the cut XI-XI after Pig. 22;

Pig. Fig. 24 is a sectional view of another embodiment;

Pig. 25: the vibration damper after Pig. 24- during use on average;

Fig. 26 is a sectional view of another embodiment;

Fig. 27 is a sectional view of still another embodiment;

Pig. 28 is a sectional view of another additional example embodiment of the pig.

η + * ο ··, · '**' · ^ ^{'59 027 / 2Τ} -

The vibration damper according to the invention consists of a. Trägerien enient 2 ₅ for example, an arm, a vibrie- .. mechanical end body, a cylindrical handle 3 ₉ concentric with the support element. 2 and can be operated by the hand of the operator, and .a coiled or spiral peder 4 with alternating small and large tortuous sections, with the peder 4 placed between the carrier element 2 and the handle 3 _e small tortuous portion is secured by welding or other suitable means, such as an annular groove 20 formed on the support member 2, to the support member 2, and each large tortuous portion cooperates or contacts the cylindrical handle 3 Oscillations remarkably attenuated »When rubber or other elastic material is used, for example as part of the cylindrical handle 3, the damper achieves a higher degree of vibration damping or absorption. The peder 4 with the specific construction described above may consist either of a single piece with alternating bulges and constrictions, or of a plurality of separate segment or peduncle units, each formed by at least a large portion and at least a small portion. In addition, the peder 4 may be fixed to the handle 3 and the support member 2 by welding, grooving, gluing with "an adhesive, etc., or else it may be held between the cylindrical handle 3 and the support member 2 by splashing on both Ends of the handle 3. As a further alternative, instead of the direct fastening of the peder 4 to the carrier element 2 or its interaction with this, an inner cylinder may be provided. In this Pail, handle 3, inner cylinder and Peder 4 can be pre-assembled as a unit «.

* _A · 5.9 027/27

Ο · ^ O f 'Γ η O

Z Z, ο η ο 3 Z - 9 -

In the Pig. 1 v / is shown in perspective. A chainsaw, at τ; The housing absorbs the drives and is referred to hereinafter as the vibrating body 1 because it is a source of vibration. The saw blade 28 is a bundle chain. The vibrating body 1 includes a support member 2, for example, an arm which is gripped by the operator. In handle 3 is pulled over an upper portion of the support element 2,. The vibration damper according to the invention belongs to a construction which the. Trägereicraent 2 and the handle 3 connects together «This is true for all now to be described in detail embodiments.

Reference will now be made to FIGS. 2 and 3, which illustrate an embodiment of the invention. In these and all following figures, like reference numerals designate like elements. On a tubular carrier element 2, for example an arm, of a vibrating body 1 a spring 4 is attached, which consists of a series of barrel-shaped spring units, which are formed by welding or other connecting elements, for example 'annular grooves 20 and locking grooves formed on the carrier element 2, This spring 4 consists of a series of barrel-shaped units, as shown, where each unit begins with a neck or constriction in which -ω-itte bulges and narrows again to the initial cut-off The envelope of the spring 4 has sinusoidal or deformed sinusoidal contours. Since the spring 4 has a plurality of constrictions of the same diameter, it can be attached directly to the support member 2 without the aid of other fasteners. On the other hand, the multiplicity of bulges with the same major on the inner surface of an inner cylinder 5V

, , "59 027/27 O H -A *! · / - ΊΟ -

be attached '' metal, which in turn is applied to the inner surface of the handle 3. In this way, the spring 4 ₅ which consists of barrel-shaped spring inserts of alternating bulges and constrictions makes it possible to fix the handle 3 firmly on the carrier element 2 and to effect the vibration damping. The inner one. Cylinder 5 ^! made of metal is covered with an outer sleeve 5 made of vulcanized rubber or other elastic material; together form the cylindrical handle 3 "The outer sleeve 5 is at both ends with flanges 7 < _s to limit the two outer End.en 6-, 6 _? the spring 4 νersehen5 so that it does not move axially. In this way, it has some vibration damping or absorbing action, an adequate grip is established, and the flanges 7-j, 72 prevent the springs 4 from being removed. If desired, the spring can be cut into separate segments at given points of the necked or buckled sections »

4 and 5 show another embodiment of the vibration damper according to the invention * In this case, the spring 4 is also fixed to the support member 2 and has the same structure as in the embodiment of FIGS. 2 and 3 ₅ but ends in contrast to In addition, the handle 3 in this embodiment consists of a single metal cylinder bent at the ends perpendicular to the axis ^{so as to} restrict annular flanges T ^ S 7p to the bulged ends 6, 6, 6 of the Spring 4 in the form of a sleeve restricts the axial movement of the spring 4 and prevents it from slipping off.

Another embodiment of the invention is shown in FIGS. 6 and 7. In contrast to the previous embodiments, it has an internal metallic

Q V: Q ^ 7 ^{'59 027/2?}

U * CJ \ J% [? & »· -11 -

Cylinder 8, which is arranged between the tubular support member and the tortuous Peder 4 with alternate constrictions and bulges and fixed on the Trägereiement 2. The two ends of the inner cylinder 8 are bent to the right in the direction of the axis to hold the opposite ends 6 , 6 , 6 of the constrictions of the peder 4. An outer metallic cylinder 8 ¹ , which forms the cylindrical handle 3, has. no splashing and is fixed to the bulges of the peder 4 by welding or a similar method. This embodiment is easy to manufacture, since the inner and outer cylinders 8, 8 'and the peder 4 can be preassembled from a series of tonnenförraiger units and attached as such on the support member 2 to complete the necessary assembly.

Figs. 8 and 9 also show a vibration damper according to the present invention. In this pail, an inner metallic cylinder 10 is provided with upright splatters 13-i-13o which are constricted with the constricted ones. , Ends 6th, 6th _? of a peder'4 'to keep them immobile. In addition, the metallic cylinder 10 has cylindrical extensions 11- "11p" ^which are secured by head screws 12, ₅ 12p to the carrier element 2 "An outer. The cylinder 10 ", which forms the handle 3, is made of elastic material, for example hard rubber, to form a pimple and to create a corresponding friction for the hand of the operator.

In the Pig "10 and 11, an embodiment is shown which in the Pig _e 8 and 9 ₀ corresponds The only difference is that der.Griff 3 of Einein cylinder 10 of this embodiment '" is made of rubber and an inner than Lining attached metal cylinder 14 to which the Peder. 4 attached "is _β In this Pail

'(SK ' r. '59 0.27 / 27

2 J ' fi f'x w * \ 4 · # 1? _

MS. " Vi * | _v / V # «Yyy? , ^ jj, _ - _,:

can, the rubber softer than when. Example of FIGS. 8 and 9,. '.

Another embodiment is shown in Figs _e 12 and 13, shown. Like all previous embodiments, it has a coiled spring 4 with constrictions which are secured by suitable means to the tubular support element 2. The bulges of the spring 4 are glued to the inner surface of the handle 3, which consists of hard rubber or other elastic material. The two ends of the handle 3 are provided with flanges .7 ^, 7p. A distinguishing feature of this embodiment is a plurality of non-slipping, annular protruding surfaces 15 formed on the outside of the handle 3. By these surfaces 15, the operator can grasp more firmly, moreover, a certain damping effect in addition to Schv / ingungsisolaTIONwirkimg the tortuous Spring 4 achieved »

A similar embodiment of the invention is given in Figs. 14 and 15, The handle 3 consists of a Hartgumraizylinder with Endflansch en 7-t _S 7 _? and also a plurality of non-slip protruding surfaces 15 ^! of foam rubber formed on the outer surface of the hard rubber cylinder. This design reduces the transmission of vibrations / even more «

The pigs 16 and 17 illustrate another embodiment, in which the spring 4 is divided into separate barrel-shaped segments, each having a constriction and a bulge and secured to the tubular support 2. The handle 3 is concentrically "mounted on the spring 4." As shown, the handle 3 is a cylinder of Kartgummi with. a plurality of annular stiffening ribs 16 on the inner surface

₍ · _ _ ^ .59 027/27

/ / Η R Fi * ·?I -13 - '

g »« -'Si »W ^ / V ₁₃ J? ζ ^ «^ _x , ^

be formed. In annular recesses 16 'formed between the ribs 16, the bulges of the segments of the spring 4 are firmly held in place. ".;. ·

In a further embodiment of the invention, shown in Figs. 18 and 19, a pair of helical springs 4 are attached to a tubular support member 2. They are attached to two. Make along the axis of the support member 2 and in a plane at right angles to this held by suitable elements at a distance. A handle 3 consisting of a metallic cylinder 5 "and an outer sleeve 5 made of rubber or another elastic material is arranged around these springs 4. Huffe 5 mounted transversely on the cylinder 5" has flanges 7-j at the opposite ends, 7p on. Although the springs are wound to a configuration different from that of the previous embodiments, the same effect as the vibration damping is achieved.

Another embodiment is shown in Figures 20 and 21. The springs 4 are similar to those in Figures 18 and 19. However, to keep them in place, see the support member and the metallic cylinder 5 ', the carrier element 2 is provided on the outer circumference with annular grooves 20, wherein the metallic cylinder 5 "has corresponding annular grooves 21 on its inner surface, so that the two ends .18 and 19 of each spring 4 in each case a set of these ring / grooves 20, 21 In this manner, the damping portions and the handle 3 are secured in position.

In still another embodiment of the invention shown in Figs. 22 and 23, spiral-e

£ »'Λ - ^. , 59 027/27

Used springs 4, which are wound in the same manner as in FIGS. 18 to 21, but of narrow, flat bands, not ausgrundnn wires were made; , ,

Figures 24 and 25 show another embodiment in which the spring 4 has a plurality of barrel-shaped units with alternating constrictions and bulges of a given diameter, the constrictions being on the tubular support member It is fastened concentrically to the carrier element 2 by a long, toroidal handle 3. It consists of a rubber cylinder with hollow sections 22, the diameter of which is changed stepwise, and a reinforcing, complementary metallic cylinder 23 with a corresponding structure, the . fixedly fitted into the rubber cylinder is _o So assumes the inner diameter of the metallic cylinder 23 from section to section of the two ends to the middle au out. As shown, only the bulges of the barrel at the two ends der.Feder 4 with the metallic cylinder 23. firmly connected * In this way absorb the Federendabschnitte even small movements or vibration Ungen of a machine or a similar unit "ITimmt the" strength of the vibrations to _s -are gradually also involved the other key portions of the vibration damping, as is shown for example in the pig ₀ 25 "The advantages of this exemplary embodiment are Comfort in handling the grip by the operator and "in steadily increasing or decreasing the vibration damping in proportion to changes in the magnitude of vibration movement". , ,

59 027/27

C- O O - -15 -

Pig. .26 shows a further embodiment of the invention. To this damper belongs a serpentine Ped'er 4 in a series of barrel-shaped units, which are arranged around the tubular Tragagerelenient 2 »The spring 4 is covered by a handle 3 ', which consists of a straight outer sleeve 5 made of rubber, the with splashing 7 <i -7p! The diameter of the segments of the spring 4 is progressively reduced from both ends to the central portion of the spring 4. Consequently, the damper acts on the same Way like that of Figs. 24 and 25.

FIG. 27 shows another embodiment as a modification of that shown in FIGS. 18 and 19. The helical springs 4 are in turn arranged as a pair in the same plane perpendicular to the axis of the 'carrier element 2. However, this arrangement differs from the previous one in that the inner and outer ends of each spring are double wound to allow secure attachment to the support member 2 and the reinforcing metallic cylinder 5 ".

Another additional embodiment, shown in FIG. 28, operates with helical springs as shown in FIGS. 18 and 19 "but they are held in a different manner." The support member 2 is provided with two. Annular grooves provided in distance sleeves 27 < "27p v / ground fitted into the hats, and the springs 4 of the vibration damping seinheit are held in pressure contact with the inner sides of the mutually aligned sleeves 27-i and 27o. On the other hand, the handle «3 consists of a reinforcing metallic cylinder 24 of small diameter, with

^) ^ y Π Γ ί * ^ 1 '^ ^ 027/27

flared ends 26, _} 26p are stranded with a larger diameter, and from a blanket cylinder 25, which is firmly fitted into the so recessed outer circumference of the metallic cylinder 24- .. Each Peder 4 acts on a. , Side with the annular step, which is formed by the flared end 26 and 26 of the metallic cylinder 24 ο. ·

In addition, it is noted that the springs 4 are firmly held between the formed annular steps and the sleeves 27-j and 27 ₂ , respectively.

Claims (8)

R RV "- ι? .- 59-027 / 27 Invention sans-pruch 1. Vibration damper for an oscillatory mechanical body, such. B * a chain saw or a motorcycle causing a vibratory movement, characterized in that the carrier element (2) provided on a vibrating body (1) for handling, z _c B. eLs arm has a cylindrical handle (3) in which a vibration damping spring (4) is provided, which has a series of small and large winding parts and is between support element - (2) and handle (3), each small winding part of the support element (2) and each large winding part of the inner Surface of the handle (3), and the vibration transmitted from the vibrating body (1) to the support member (2) is absorbable by the vibration-damping spring (4). 2.-vibration damper according to item 1, characterized in that the cylindrical handle (3) consists of an outer sleeve (5) made of rubber or other elastic material, which is connected to an inner cylinder (5 Ό made of metal, and that the vibration-damping Spring (4) is divided into a plurality of barrel-shaped units arranged in an axial row, the two outer ends (6, 6p) of the spring (4) of flanges formed on both ends of the outer sleeve (5) (7-j; 7p) are kept *. 3 »A vibration damper according to item 1, characterized in that the _{S-zj-cylindrical} handle / 3) consists of a single metallic cylinder and the two outer · ^: 39 027/27 Ends of the vibration-damping spring (4) are held by flanges (7-7p) attached to both ends of the metallic cylinder 4 «Schwingraigsdämpfer after point 1,. ', Characterized in that the. cylindrical handle (3) consisting of an inner and an outer metallic cylinder (8, 8 '), wherein the two cylinders (8, 8') are held at a suitable distance from each other, and that the two outer ends (6 ..; 6g) of the vibration-damping spring (4) are held in this space by flanges (9-] j 92) arranged at both ends of the inner metallic cylinder (8). 5e vibration damper to Hinkt 1, characterized in that the cylindrical handle (3) off. an inner metallic cylinder (10) and an outer cylinder (10 ") of rubber or other elastic material which are at a suitable distance from each other, the inner metallic cylinder (10) providing cylindrical elongations (11 \ ; 11p) ^ ¹ both Having ends which are fixed by cap screws (12-; 12p) to the support member (2), and-also at both ends with flanges C13-1, 13p) is provided, through which the two outer ends' (6 ^ ·; 6p) of the vibration damping spring (4) are held in the space _e 6 _β vibration damper according to item 1 , characterized in that the cylindrical handle (3) .from an inner metallic cylinder (10) and an outer cylinder (10 ") made of rubber or other elastic material, wherein both cylinders (10; 10" ) are mounted at an appropriate distance from each other, and the inner metallic cylinder (10) has cylindrical extensions (11-p Ho) P fi 0 1 59 027/27 at both ends, which by means of cap screws (.12. *; 12o) are fixed to the support element (2), and. · Also provided at both ends with splashing (13 ^ 5 13 ₂ ) through which the two outer ends (6, 6, 6) of the vibration-damping peder (4) are held in the space. wherein the outer cylinder (10 ") of elastic material is connected to a metal cylinder (14). 7. A vibration damper according to item 1, characterized in that the cylindrical handle (3) consists of a rubber cylinder made of synthetic resin or other elastic material and is provided on the outer periphery with a plurality of sliding annular peripheral surfaces (15, 15) ') is provided _c 8. Vibration damper according to item 1, characterized in that the cylindrical handle (3) consists of a rubber cylinder: having at the outer periphery a plurality of non-lubricating circumferential surfaces (15 ') made of sponge rubber. 9 _e vibration damper according to item 1 _$ characterized in that the cylindrical handle (3) consists of a rubber cylinder having a plurality of annular stiffening ribs (16) located on the inner periphery, the vibration damping springs (4) are held with their elevations in between the annular recesses (16 ^f ) formed by the stiffening ribs (16). 10. Vibration damper according to item 1, characterized in that the vibration-damping Peder (4) consisting of a plurality of in the same plane one behind the other, at right angles to the support axis adjusting spring units existing 59 027/27 11. Vibration damper according to item 1, characterized in that the vibration-damping peder (4) consists of a multiplicity of helical spring units arranged one behind the other in the same plane at right angles to the carrier axis, whereby both the inner and the " the outer end (18; 19) 'of the spring (4) is received by annular grooves (20; 21) mounted in the support element (2) and in the inner metallic cylinder (5 ") of the handle (3) , 12.-vibration damper according to item 1, characterized in that the vibration-damping spring (4), a plurality of plank material existing in the same plane and at right angles to the carrier axis standing Pedereinheiten is formed. 13. "vibration damper" according to item 1, characterized in that the cylindrical handle (3) is a thick-walled rubber cylinder having hollow sections which are gradually reduced in diameter from the middle section to the rear, and. with a reinforcing metallic cylinder (23) · are connected. , 14 "vibration damper according to point T, characterized in that the cylindrical handle (3) ein'gerader Gummizylin-. the spring is connected to a reinforcing metallic cylinder (23), wherein the intended vibration damping end (4) consists of a plurality of barrel-shaped units extending from both ends (6, 6o) of the spring (4) to the middle section to successively reduced in diameter « 2 _Λ '53 027/27 2
Cl UU 15. Vibration damper according to item 1, characterized in that the vibration-damping spring (4) consists of a multiplicity of spring units, v. The inner and outer ends of which are spring-wound twice, 16c chases he steam according to item 1, characterized in that the cylindrical handle (3) consists of a metallic cylinder (24) of small diameter, the land (26 .. j 26p) are widened, the part of Smaller diameter cylinder (24) receives a cylinder (25) made of rubber or other elastic material, and the units of helical springs (.4) housed within the cylinder (24) in the region of its revaluation, into which 2) fixed cuffs (27-j; 27o) intervene, are held _o For this 73 pages drawings