Terminology

[Normk]

Constant duty relay: This is an important consideration because only some relays are intended to be in operation for extended periods of time. Most "Bosch type" relays are constant duty but starter solenoids (relay) are not. If one selects an intermittent or non-constant duty relay for such use as headlight, main power, etc. the relay will burn out or melt and fail.

Typical horn relay service does not require a constant duty so recovering a horn relay for other use may not be ideal.



By the way, make a trip to your local "Pick-a-Part" self serve auto wrecker and buy a handfull of relays for projects. While you're there, get some bulbs with sockets and buy a wiring harness off any car.

The wiring harness can often be purchased for a few dollars and is a gold mine of color-coded wires, connectors and handy stuff. Rather than wiring all your accessories with the same white, red, blue and black wires from spools of wire, select a blue with green tracer for one, red with yellow for anther, etc. Record the colors on your wiring diagram and life is easier.

[Normk]

We need to keep this going as terminology confusions cause a lot of problems.

Signal relay- in the trade this is a conventional relay which is not the signal flasher unit. The maker's shop manual often uses this term so it causes confusion.

Signal flasher- the blinker unit which causes the lights to flash. While technically a "relay" the trade does not refer to it in this manner. The confusion resulting will be similar to the "starter relay" versus "starter solenoid" one.

[tatu]

A starter SOLENOID is used on automotive (and aircraft) starters. This combines the relay from the above with a bigger SOLENOID that moves the engagement gear onto the flywheel of the engine. As the gear fully engages, the solenoid also closes the switch for the high current drive, causing the starter motor to turn. The mechanism was the invention of Vincent Bendix, founder of the Bendix Corp., and was a huge advance in automotive technology. The mechanism is still referred to as a "bendix" among aviation mechanics. Now that I think about it, the bendix drive takes a good bit of current itself, and there is usually a separate starter relay for it in cars.


For grins, I just checked the longitudinal engined Honda Goldwing and BMW K-bikes, both of which use a sprag clutch. Maybe the Ural or something like that uses a Bendix solenoid drive.

What you have described here is a pre engaged starter, and is not a Bendix. These are the norm these days.
A Bendix starter has the mechanism of a gear that slides on a spiral that throws the starter gear into the ring gear as it begins its rotation and is then pushed back by a spring and the flywheel ring gear as it accelerates past the starter speed.
Hope this helps.

[Normk]

In automotive and truck repair trades, a "Bendix" refers to any starter drive although this does not apply to bikes in my experience as they lack this type of mechanism.

Someone mentioned the term "Sprag clutch" as referring to the type of overrunning clutch found on most modern motorcycles. In trade terms "Sprag clutch" is understood as an overrunning clutch which is installed within an assembly however, just so everyone knows, these are roller type overrunning clutches. This type of clutch is common within automatic transmissions and some older type overdrive units. A "Sprag" is an elongated dog which is placed at an angle within the clearance between two drive members. They are not found in many applications today as roller clutches have replaced them but the terminology has remained. I don't recall the term as being used in the motorcycle repair field but someone may have. Harley is a good possibility as they have a different history than the others. Haven't worked in a Harley shop but have sold tools into some....

All that and a couple of bucks will get you a cup of coffee at Mickie D's.

Fun knocking these terms around and who knows but something may be useful to someone....

What you have described here is a pre engaged starter, and is not a Bendix. These are the norm these days.
A Bendix starter has the mechanism of a gear that slides on a spiral that throws the starter gear into the ring gear as it begins its rotation and is then pushed back by a spring and the flywheel ring gear as it accelerates past the starter speed.
Hope this helps.

[Normk]

Screw: a threaded fastener which goes into a structure.

Bolt: a threaded fastener which is used with a nut.

Note that the same fastener can be either a bolt or a screw depending on application. The reason for the "can" reservation is that fasteners such as carriage bolts are not used without nuts.

Most non-technicians seem to believe that a bolt is a bigger fastener with a hex, Allen, Torx, type head while a screw is a small fastener turned by some "screwdriver" drive such as slot or Phillips. Not so. A 1" hex head capscrew is not small. The "cap" portion of the name means that it has a head larger than the shank.

[sparki]

a bolt doesn't have a thread along it's entire length.... while a "set screw" does

[Graham]

Screw, what I got when I bought my GS1100.
Setscrew, planning to get a good running GS1100 off Ebay like I did.
Bendix, the position your in when you buy an old junk GS1100 like me.
Sprag, the last girl I picked up in a bar.
Sprag Clutch, what I was in when we got on the dance floor.
Bolt, what you do to a door to keep out sprags.
HIH, how in hell do I leave with out waking the sprag up?

Old phrases;
Ronda still riding her Honda.
The Kaw is giving milk.
Skuzuki.
Yamaha-ha-ha-ha.
BSA, bastard stopped again.
Lucas, the inventor of darkness.

[Normk]

Carriage bolts, for example typically are threaded for their full length. The standard amount of thread on a capscrew or machine bolt (what we use on our bikes) is threaded either 2-1/2 or 2-3/4 times it's length plus 1/4", if memory serves although I learned that SAE (Society of Automotive Engineers) standard about 50 years ago.

Many low grade (Grade 2 or lower) bolts are full length threaded for marine applications. Amount of thread has no bearing on whether it is a screw or a bolt. That is based on whether it threads into a part (screw) or is used with a nut (bolt).

A "set screw" sometimes has threads for its full length and sometimes not. The amount of thread has nothing to do with its role in applying axial effort by use of threads to force the end of the set screw against the work.

a bolt doesn't have a thread along it's entire length.... while a "set screw" does

[hampshirehog]

This is the old 2 (well 3 really if we include Canada along with the US and exclude the rest of the colonies...) nations divided by a common language.

In the UK Sparki is right about a set screw and a bolt. Carriage bolts don't necessarily have threads on their whole length - they are just a bolt with a circular head and a square bit underneath. And the length of thread on a capscrew or machine bolt can be any length. Capscrew is a 'new' word over here and is commonly used by people who aren't sure how to spell Allen / Alen / Allan / Alien bolt.

Graham is also wrong with the meaning of BSA. It's 'Bastard....start! Aaargh'.

And everyone knows that a nail is 13 amps - for universal use in British homes.

[Normk]

Washers and their usage often get people into trouble.

A washer is a device which is placed between two fasteners or a fastener and the work piece. Everyone is familiar with many types such as flat washers/plate washers, lock washers (many types of these), and so on.


One problem comes from a misunderstanding of the quality of flat washers. A flat washer or plate washer is simply an annular ring placed between the fastener and something else for some purpose. The trap is in failing to understand that these washers have differing characteristics depending on the material and even shape.


Flat washers are made from various materials but in simple terms we may wish to confine consideration to that of a "soft" washer versus a "hardened" washer as this is easy to contrast. If one uses a US Grade 2 SAE bolt (equivalent to Metric Grade 5.8) or screw with a washer, one can virtually ignore the washer's material in selection.


For reference, here is a section quoted from Bolt Science.com:



How do metric strength grades correspond to the inch strength grades?
Some details on conversion guidance between metric and inch based strength grades is given in section 3.4 of the standard SAE J1199 (Mechanical and Material Requirements for Metric Externally Threaded Steel Fasteners).
Metric fastener strength is denoted by a property class which is equivalent to a strength grade. Briefly:
Class 4.6 is approximately equivalent to SAE J429 Grade 1 and ASTM A307 Grade A
Class 5.8 is approximately equivalent to SAE J429 Grade 2
Class 8.8 is approximately equivalent to SAE J429 Grade 5 and ASTM A449
Class 9.8 is approximately 9% stronger than equivalent to SAE J429 Grade 5 and ASTM A449
Class 10.9 is approximately equivalent to SAE J429 Grade 8 and ASTM A354 Grade BD
For information there is no direct inch equivalent to the metric 12.9 property class.

Obviously, one big problem in fastener selection will arise where people confuse "Standard" or inch size fastener strength ratings with those of Metric ISO standard!



Let's return to the selection of washers: digging around in the washer bucket under the bench or selecting some washers from the bulk bin of the local hardware store can inject an unwanted problem into your work.


Let's assume that you are tightening a metric Grade 10.9 (approximately US Grade 8) but select an unhardened flat washer. The tension applied by a properly tightened Grade 10.9 fastener can apply so much clamping pressure to the washer that the washer begins to squeeze out of the joint. The pressure has become so high that the steel becomes plastic. I use this term frequently in the hope that it will allow someone to appreciate the risks entailed.


Let's assume that you have placed a soft washer into a connecting rod bolt, just for example. Now, the bolt and nut are tightened to the correct degree and the engine assembled. At this point it is necessary to appreciate that the bolt has been tensioned by this tightening, which is to say that it has been placed under axial loading and partially stretched.


The stretch is similar to that of an elastic band and is something to which I have referred in other posts because this effect is important in the functioning of threaded fasteners. The connecting rod bolt's function is to apply more clamping force to the junction of the connecting rod cap and connecting rod than that which is applied by the rod and crankshaft action. The washer is not tough enough to resist the pressure so it deforms which reduces the clamping force applied by the connecting rod bolt onto the connecting rod cap & rod junction.

The effects on the washer are in a mirror image to that on the bolt which I will attempt to outline.


OK, so big deal, right? More BS crap someone found in a text book, right? Have it that way if you wish but the connecting rod doesn't give a rip about the myths which people choose to believe, it simply does its job until something fails.

OK, so the clamping force applied to the connecting rod bolt is not less that intended.

That is not debatable by even the doubters as anyone should see that as evident although it is simple to set up a test procedure to prove this is the case. We used a small hydraulic device for this purpose during apprentice training and journeyman upgrading classes.


We now have a situation in which the connecting rod bolt is "loose" but let's assume that the nut does not release further and the engine continues to run because this is what would usually happen. Every time that the piston reaches the top of a stroke, the piston and connecting rod must be stopped in their upward motion by the crankshaft throw. When the piston accelerates downward, the force required for the acceleration is applied by the crankshaft throw during the intake stroke. Obviously the crankshaft throw applies this force by working against the connecting rod cap which uses the connecting rod bolts to transfer the force from the connecting rod cap to the connecting rod, not question there.


So what are the effects on the connecting rod bolts? First it is necessary to recognize that the steel bolts are elastic, they stretch when something pulls on them. They will stretch for a certain length in response to tension and, within this range, will return to their original length. This stretch is referred to as the elastic range of the fastener and is roughly equivalent to the elastic stretch range of a rubber band. If greater tension is applied to the fastener, it will continue to stretch but the effects within the structure of the steel become different. During this range the steel begins to deform/tear/flow internally through this range which we call the "yield range" of the fastener. The increase in length during the yield phase will not be recovered when the tension is released from the fastener.


OK, engine running and all the connecting rod bolts having the correct hardened washers are being pulled and released in operation as normal. They have greater tension applied to their clamping action than that which is applied by the pull of the engine forces so they don't stretch and release in operation. There is no internal working of the steel through stretch and release so no metal fatigue occurs over time. But what about the bolt having the softer washer which has yielded and so reduced the bolt's clamping force?


In this case, the bolt is not tensioned to a degree greater than that being applied by engine forces so the bolt stretches and recovers, stretches and recovers during every stroke, millions and millions of times. Over time the material begins to fatigue and finally, the bolt breaks creating a catastrophic failure. On post mortem, someone holds forth with great authority that some idiot (of course lacking their deity-like qualities) must have over tightened the bolt. Or perhaps they slander the manufacturer for using cheap bolts.


The truth, of course, is that an over tightened bolt/over tensioned bolt, would have failed very soon after assembly because if the high force involved. The fact that the bolt endured for a significant period of operation may point to the possibility that it was under tightened. If this was due to the use of a soft washer......


The same effect is evident in many other circumstances in which a desired clamping force is expected from a fastener. This clamping force may be lost if the washer selected is not tough enough for the application but this issue is virtually ignored by the untrained.


One of my very, very favorites is the use of stainless washers which are typically soft as butter and which yield to even moderate clamping. But, gosh they do look pretty! Ditto any material which is not capable of withstanding the forces involved.

Brake, steering and suspension parts are generally intended to be secured by a certain degree of clamping force. This clamping force reduces the shear and bending forces applied to the fastener.


Sorry that these posts tend to extended length but I'm simply trying to do my bit in the hope that it will save someone some grief. Just an attempt to pay forward with the currency available despite that I know some become vexed.

[Mysuzyq]

Agreed, it took me quite a while to figure out what HTH meant. I had one particular tech support guy who used it all the time.

HTH is also = Hands To Heaven......you know you've got big problems when your tech support/ mechanic/ doctor resorts to this.