GB2396420A - Chain elongation gauge - Google Patents

Abstract

A gauge which gauges or measures chain elongation by means of a pivoting niche 5, a tension tine 6, and a number of variations which facilitate gauging and measuring. The gauge includes a stop surface 7 for an adjacent roller 10 in use. A further stop surface is provided (at 26, fig.5). The tine 6 may include a scale 15 or indentations 17 to assist gauging. Other embodiments are disclosed and claims. One embodiment includes a slidable measuring edge (42, fig.12) in addition to tine 6.

Description

-1 CHAIN ELONGATION GAUGE

This invention relates to a gauge which measures the elongation of power transmission bush roller chain.

It is intended to include industrial drives, conveyors, automotive, motorcycle and bicycle chains based on the Renold patent of the 1880's and further improvements such as sealed "a"- ring and "x"-

ring chain.

When a power transmission chain wears, it elongates, and after a certain amount of elongation has taken place, the rate of wear quickly accelerates, power in the drive is lost, excessive strain is put on bearings and sprockets, and ultimately breakage occurs.

Chain breakage can be dangerous in industrial situations and even more so in the case of motorcycle drive applications.

To this end chain manufacturers specify maximum permitted chain elongations which when attained or exceeded the chain must be replaced.

Measuring chain elongation should be done under a certain amount oftension,which in most cases involves removal of the chain from the drive, requires accurate measurement (1% can be the maximum elongation allowed), and usually involves a lengthy calculation and reference to manufacturers tables.

Consequently such measurement is reluctantly and rarely carried out.

The purpose ofthis invention is to allow quick and easy tensioning and measurement of such chains whilst in situ on the chain drive.

According to the present invention this is done with a tool which has an accurately profiled pivot niche which when inserted between the inner plates ofthe chain the tool is pivoted so that an accurately profiled tensioning tine may enter between two rollers a set distance and inclination away from the niche, and as pressure is applied on the tool in the region of the tine, it is forced further between the rollers, so tensioning the spanning chain.

The amount the tine penetrates between the rollers being a measure of chain elongation. There are then a number of variations of the present invention in which this penetration and so elongation may be gauged or measured.

Specific embodiments of the invention will now be described by way of example.

NB on all sections through bush roller chains the roller, bush and pin sections are shown simply as circle sections for clarity.

-2 Figure 1 sho ws a plan view of a typical simplex roller power transmission chain.

Figure 2 sho we a perspective view of a basic elongation gauge.

Figure 3 shows a basic elongation gauge with the preferred pivoting niche style.

Figure 4 shows a new, unelongated chain section (such as section 21-21 in figure 1) with a basic elongation gauge in use.

Figure 5 shows an elongated chain (section 21-21) with a basic elongation gauge in use and registering the chain is at the maximum allowable elongation The chain side plates are omitted for clarity.

Figure 6 shows a semi elongated chain section 21-21 with an elongation gauge in use with tine graduations added.

Figure 7 shows a view of a chain roller or bush section in contact with the tensioning tine with measuring indents and elongation amount markings added.

The chain side plates are omitted for clarity.

Figure 8 shows a variant elongation gauge in use with multiple stop surfaces between the tensioning tine and the pivoting niche which are used once the roller is in contact with the original stop surface at the top ofthe tine.

The chain side plates are omitted for clarity.

Figure 9 is a further variant along the lines of figure 8 but with a single stop surface between the tine and the niche.

The chain side plates are omitted for clarity.

Figure 10 sho we a gauge with a roller feeler element with a special scale arrangement.

The chain side plates are omitted for clarity.

Figure 11 sho ws cross section 25-25 from figure 10.

Figure 12 shows a gauge with a vernier slide arrangement.

The chain side plates are omitted for clarity.

Figure 13 sho ws cross section 45-45 from figure 12.

Figure 14 shows a basic chain elongation gauge with small and large diameter rollers superimposed and being gauged.

figure 15 shows a roller diameter compensating gauge with circled shown in detail in figure Figure 16 shows circled areas of figure 14 in detail with both smallest and largest roller positions superimposed.

-3- Referring to figure 3 of the preferred basic elongation gauge there is a pivoting niche 5, a tensioning tine 6, stop surface 7, pressure surface 8,and gauge identification markings 27.

The markings 27 are important because different manufacturers may vary the dimensions of roller diameters, distance between inner side plates and possibly even the chain pitches themselves.

Therefore it is important that the correctly dimensioned gauge is identified for use on particular chain types.

When the gauge is in use on an unworn and unelongated span of chain 13, as in figure 4, the pivot niche 5 is located on roller 9 and subsequently pivoted so that tension tine 6 comes into contact with roller to and moderate (hand) pressure is applied to the chain in the direction of arrow 1 1 and simultaneously to the gauge along arrow 12.

The tine 6 reacts against the roller lOand likewise the pivoting niche 5 against roller 9 so tensioning the span of chain 13 until equilibrium is reached and tine 6 will no longer move relative to roller 10.

The amount the roller 10 moves relative to tine 6 is a measure of the chain elongation.

As may be seen be seen from figure 4,after initial contact, the tine 6 has hardly moved relative to roller 10, and so by visual inspection, and by feel the chain can be determined as below the maximum elongation.

There would be a spongy "feel" when applying pressure along arrows 11 and 12, and may be more predominantly be felt along chain span 13, by simultaneously sqeezing along arrows 27.

Such a gauge will have to be tailored to suit a particular chain with regards to it's pitch, roller diameter, and distance between the inner plates.

Referring to figure S the basic gauge is measuring a span of chain 14 which is has just reached the maximum recommended chain elongation and by applying moderate hand, finger or thumb pressure along arrows l l and 12, the roller 10 has moved along tine 6 sufficiently so that it has come to rest hard against the stop surface 7, which may be seen and certainly felt by the user.

This hard stop may also be simultaneously felt between rollers 9 and to against a further stop surface 26 by squeezing along arrows 27.

In figure 6 simple graduations 15 are shown on tine 6 in order to visually estimate the amount elongation, wear or life left in the chain.

In figure 7 indentations (recesses or niches) 17 are shown in tine 6 along with markings 18 which may signify the degree of wear or life left in the chain.

When the roller 1 0 moves along tine 6 and over indentations 17 a vibration is felt by the user and so by counting the number of vibrations felt and comparing to the markings 18, an elongaion measure may be made.

- Figure 8 shows an example of a gauge with an alternative tine stop surface 28 which when roller 10 makes contact with stop 28 the elongation signified by marking 37 would be known to have taken place.

Furthermore whilst simultaneously keeping the surface 28 and rollerl 0 in contact the user may squeeze the chain spanning rollers 9 and 10 along arrows 19 to test if any rollers will make contact with further stop surfaces 20.

When a contact is made by a roller on a stop surface 20 then the degree of elongation signified by markings 38 is known to be attained, 90% in this case.

Figure 9 is a variant of figure 8 whereby there is a continuous surface 36 (between points 34 and 35), which whilst roller 10 is in contact with alternative tine stop 28, each roller in turn (between rollers 9 and 10) may be squeezed in the direction of arrows 19 to test if it will touch surface 36.

When such contact has been made, comparison with markings 38 would enable a user to infer the degree of elongation attained, and in the case of figure 9, it can be seen that 90% elongation has taken place.

The surface 36 (between point 34 and 35) need not be a straight line, but could be some form of curve.

A further example of an elongation gauge that may give a more accurate reading of elongaion and has the advantage of retaining elongaion readings for more convenient remote inspection is shown in figures 10 and 11, which has a feeler 23 which pivots in a stiffmanner about point 24, so as it will retain it's position when handled alter an elongation measurement has taken place.

The feeler 23 has a portion 29 which makes contact with roller 10.

The feeler 23 is reset to the minimum elongation reading position prior to measurement. During an elongation measurement the roller 10 moves up tine 6 and simultaneously the feeler portion 29 (also in contact with roller 10) pivots about point 24.

The subsequent position of feeler 23 relative to the gauge body is a measure of the elongation. Furthermore there is a measuring edge 33 on feeler 23, which when in use intersects a line 32 (shown as a dotted line as it continues behind feeler 23 in figure 10).This intersection is compared to graduations 30 and markings 31, and so an elongation reading, chain wear or life measurement may be made.

In the case of figure 10 there appears to be approximately 71% of maximum elongation. Other variations of this feeler scale arrangement may involve any combination of the following: a straight or curved line 32, a straight or curved measuring edge 33,and a set of linear or non linear graduations 30.

The markings 31 and graduations 30 could also denote life left in the chain or other quantities.

-s - Referring to figures 12 and 13 there is shown an example of a vernier type gauge with a slide element with a grip 39, a measuring edge 42(which is curved on a radius 43 from point 48) and a vernier scale 41.

When the gauge has tensioned the measured chain as previously described, the vernier slide may be slid by means of grip 39 until it makes contacts with roller 47.

The slide may be locked in place (or not), removed from the chain, and by means of co-

operating vernier scales 40 and 41 an elongation measurement may be made.

An obvious development of this version would involve replacing the vernier mechanism with an electronic measuring device with a digital read- out.

In some chains, especially motorcycle chains, the diameter of the rollers can vary between various manufacturers and designs for any given pitch.

Clearly in this case the basic gauges will not work, since these same chains are often sealed "a" and "x" ring types which have a maximum recommended elongation of 1 %, which cannot be accurately enough be gauged when roller diameters may vary between 10.16 and 11.10 mm diameter for S/8" pitch chain.

This discrepancy is shown in figure 14 as the difference between the centres of the large and the small rollers, i.e. the difference between dimensions 73 and 74.

Therefore, referring to figures 15 and 16 a further embodiment of the invention is a roller diameter compensating gauge.

In this gauge there is a niche 49 which can accommodate both the smallest roller 50 and the largest roller S1, and a combined tensioning and gauging profiled tine 57 (obviously there could be a separate tension tine and gauging tine but this would be less economic). To gauge a chain's elongation, referring to the small rollers 54 and 61 in (figurrl 6),when the chain is at the maximum recommended elongation (as shown), moderate pressure is applied to roller 54 in the direction of arrow SS, so that contact is made between the roller 54 and the tensioning profile 66 oftine 57, so that a reaction force 56 acts on roller 54 to tension the chain between roller 54 and roller 50, whilst simultaneously applying similar pressure to roller 61 along arrow 60, an unmistakable solid sensation and clunk will be felt by the use due to the reaction force 58 of roller 61 contacting the gauging profile 67, oftine 57 at point S9. This gauging contact can be confirmed by checking that roller 61 can no longer rotate freely.

Any elongation above this maximum recommended point will also result in this solid feel and inability to rotate, at roller 61 when gauged as previously described.

On the other hand if the chain is below the maximum recommended elongation, the contact of roller 61 with the gauging profile 67 of tine 57 is not possible, and this roller 61 will feel spongy when force is applied to roller 61 along arrow 60.

Furthermore roller 61 will still be able to rotate, confirming contact win gauging profile 67 has not been made, and therefore maximum elongation not reached.

-6 the case of the largest rollers 62 and 64 (shown in dotted lines in figure 16) and with the chain at maximum permitted elongation, it is not possible for roller 64 to reach a similar position to roller 54 as it can be seen to interfere with the tensioning profile 66 oftine 57.

Therefore to accommodate and compensate for this discrepancy the tensioning and gauging portions of tine 57 are curved in such a way that if rollers 62 and 64 are displaced by angle 68, rollers 62 and 64 both simultaneously contact tine 57 at either point 69 or 72 when the chain span is at the maximum recommended elongation, and so enable gauging as previously described.

For roller diameters in between that of rollers 54 and 64, the tine 54 is curved accordingly so that it may operate as previously described in the case of larger rollers 62 and 64.

Furthermore and in practice this curve may be a circular arc emanating from either roller centres 53 or 52 (or points in between) and arcing between points 59 and 69.

The tensioning profile 66 oftine 57 in the preferred embodiment would be a straight line, as this would enable easy checking the tine 57 for possible damage or bending.

Claims (13)

-7 CLAIMS CHAIN ELONGATION GAUGE

1 A basic chain elongation gauge as in figure 3, with a pivot niche S. tension tine 6, and gauge stop surface 7.

2 As claim 1, but with an additional gauge stop surface 26, as in figure 5.

3 As claim 2, but without gauge stop surface 7.

4 As claims 1,2 and 3, but with tine graduations 15 as in figure 6.

5 As claims l,2, and 3 but with tine indents 17 and markings 18 as in figure 7.

6 As claim 1, but with additional gauge stop surfaces 28 and 20, along with markings 38, as in figure 8.

7 As claim 1, but with additional gauge stop surfaces 28 and 38, along with markings 38, as in figure 9

8 As claim 1, without gauge stop surface 7, but with roller feeler 23 pivoted about point 24, with portion 29in contact with roller 10, markings 30 and 31.The gauge body has line marking 32, which intersects with roller feeler edge 33, as in figure 10.

9 As claim 1, but with the addition of a vernier measuring device, comprising a vernier slide with grip 39, scale 41 and a measuring tine with measuring edge 42, and an appropriately shaped body 46, to facilitate vernier gauge measurement, as in figures 12 and 13.

10 As claim 9, but replacing the vernier scales with an electronic measuring device.

11 A chain gauge which compensates for different roller diameters, with a pivot niche 49, a combined tensioning and compensating gauge tine 57, as shown in figures 15 and 16.

12 As claim 11, but with separate tension tine and separate compensating gauge tine.

13 A chain gauge (and variants of 3 substantially as herein described and illustrated in the accompanying drawings.