Wing Nut and belt tensioning

[dawz]

we have a 3 B-Type V-belt tensioner for engine with a spring pulling the tensioner roller. The spring is then connected to a stud/hook through the cabin and wing nut is used to pull up the spring to increase the belt tension. 2 wing nuts are used, one on top of console and one at the bottom of console.

Wing nut with spring washer and common washer:

Recently we had a case of loose wing nut and causing damage to thread stud. I have thought of many ways to make it not loose, among them are pvc washers, spring washers, curved washers, Nord locks. I'm sure nord-locks aren't suitable for this application due to belt requiring adjustment after operating for some time. The criteria is not to use spanner to fasten.

the damaged thread:

I had an idea of making a collar to prevent thread contact with metal sheet, but this requires a spanner.

background: Wing nut was used because there was a complain about the v-belt coming loose and operators in the plantation are unable to adjust the belt due to a lack of spanner. So wing nut was selected due to convenience in adjusting belt tension.

I'm sure this invites a lot of criticisms and ideas because, belt tensioning and hand turning doesn't go hand in hand. If you have a better idea, I would love to hear.

For now, belt tensioner was fastened with wing nut, spring washer and common washer with a spanner. But I don't have a convincing enough reason to the team as to why we need to use spanner to fasten the stud other than to prevent loosening/vibration damage to the stud.

 

[TugboatEng]

In the marine industry my favorite manufacturer switched from gear drive pumps to belt driven. The gear drive systems were high maintenance. The belt drive systems are 15+ years old now on original belts without re-tensioning.

Your spring is not allowing sufficient tension to prevent wear. There should not be need for regular adjustments. If you do require regular adjustment consider a different belt profile. VX is the most modern profile and lasts much longer than other profiles.

Increased belt tension increases bearing life because it keeps the support bearings from spinning their outer races in the bearing housings.

If you do all of this and are still experiencing excess wear consider using additional belts.

 

[MintJulep]

Double star knobs?

https://dimcogray.com/knobs/thru-hole-knobs/

An adaptatation of a caulking gun trigger/ratchet, or trigger clamp?

 

[dvd]

Adapt a turnbuckle to provide push/pull - an anti-rotation bar could slip into the body to prevent turning after adjustment.

 

[dawz]

In the marine industry my favorite manufacturer switched from gear drive pumps to belt driven. The gear drive systems were high maintenance. The belt drive systems are 15+ years old now on original belts without re-tensioning.

Your spring is not allowing sufficient tension to prevent wear. There should not be need for regular adjustments. If you do require regular adjustment consider a different belt profile. VX is the most modern profile and lasts much longer than other profiles.

Increased belt tension increases bearing life because it keeps the support bearings from spinning their outer races in the bearing housings.

If you do all of this and are still experiencing excess wear consider using additional belts.

15 years without re-tensioning? that's beyond impressive! I have always thought that V-Belts require constant tension adjustment because it can get "too tight".

The engine of this system is using V-belt. To leave it without adjustment during operation for 6 months is already an impressive feat. Give it 5 years without belt re-adjustment and I will be already thanking God.

I have cases of broken spring before due to vibration and snapping of the spring end. And, from what you mention, looks like over-tensioning does not exist.

Double star knobs?

https://dimcogray.com/knobs/thru-hole-knobs/

An adaptatation of a caulking gun trigger/ratchet, or trigger clamp?

Plastic is a concern.. as it is subjected to warm temperatures and possibility of degradation.

Adapt a turnbuckle to provide push/pull - an anti-rotation bar could slip into the body to prevent turning after adjustment.

you mean a turnbuckle with a handle/ratchet?

 

[Brian Malone]

dawz your proposed designs seems quite reasonable.
Pros:
1. Cost
2. Simplicity
3. Ruggedness
4. Access completely from one direction - topside/operators' side
5. Minimal change to existing design and corrects the known failure mode.
6. Gets rid of the underside wingnut, thus eliminates the need to access a wing nut on the underside of the console.

Cons:
1. Tool (spanner)required - but the tool is a common wrench (spanner)

I think your design change is good. I suggest you skip having the wing nut welded to the spacer collar. No benefit gained and this collar can free float with the wing nut to provide accommodation for assembly variations.

 

[MintJulep]

All-meatal knobs are a thing.

https://www.jwwinco.com/en-us/produ...ated-with-Tapped-Through-or-Tapped-Blind-Bore

 

[Brian Malone]

dawz Actually, I think I see why you are proposing welding the collar to the wingnut - to eliminate wear on the threads of the rod due to vibration and contact with the structure. I was envisioning the collar being bronze or brass.

 

[mfgenggear]

dawz

over thinking this . add a locking washers. then use low strength thread locker like loctite.
it will prevent wingnut from becoming loose from vibration. also an old mechanic tip. use a nut under the wing nut.
it will lock the wing nut from becoming loose. i still recommend the the thread loctite.

 

[dawz]

dawz Actually, I think I see why you are proposing welding the collar to the wingnut - to eliminate wear on the threads of the rod due to vibration and contact with the structure. I was envisioning the collar being bronze or brass.

Brian, indeed I was trying to space out the threads so that it doesn't vibrate with the metal sheet.

All-meatal knobs are a thing.

MintJulep, I have thought of this before. But to double it stacking/locking one another seems pretty tall and the threaded hook does not have enough length to accommodate 2 metal knobs.

dawz

over thinking this . add a locking washers. then use low strength thread locker like loctite.
it will prevent wingnut from becoming loose from vibration. also an old mechanic tip. use a nut under the wing nut.
it will lock the wing nut from becoming loose. i still recommend the the thread loctite.

mfgenggear, for this wing nut belt tensioner, it requires re-adjustment after some time. As TugboatEng mentioned, spring is not hard enough to prevent belt wear. I can use loctite in my factory, but when in customer's hands, they don't go to that length of applying loctite and hand tight them.

Personally, I love loctite too, we use them a lot here.

What do you guys think about NORD-LOCKS? I contacted Nord-Lock and they mentioned that it can be re-use about 8 to 10 times. I checked the clamping force for M8 sized Nord Lock is about 29Nm. Hand tightening torque can only go to 1.5Nm based on what i have found so far, means eventually spanner is still needed for nord locks.

 

[TugboatEng]

Nord-Locks require a minimum torque to imprint the washers into the surfaces. You will not achieve this torque without a fairly long wrench.

 

[TugboatEng]

If you need it to be secure use a threaded shaft collar and replace the included socket head cap screw with a thumb screw or T bolt.

Example:

Shaft Collars, for 3/8"-16 Thread Size, 303 Stainless Steel

https://www.mcmaster.com/6438K48

 

[Brian Malone]

Using TugboatEng's suggestion of a threaded shaft collar with a T-bolt or L-bolt replacing the OEM cap screw with your spacer collar with a topside wingnut might get you a solid spanner free solution. If the operators have a convenient and secure belt tension adjustment mechanism maybe the belt life will be improved.

Your spacer collar protects the threads not in engagement, the wingnut and threaded collar allow quick adjustments without needing tools. Looks pretty promising . . .

 

[geesaman.d]

I'm thinking root causes - this is coming loose because the grip length between the wing nuts is so very short. Can you a bushing into the plate where the stud passes through, spreading out the wing nuts and adding elasticity? Grip length is an excellent anti-vibration mechanism.

 

[dawz]

If you need it to be secure use a threaded shaft collar and replace the included socket head cap screw with a thumb screw or T bolt.

Example:

Shaft Collars, for 3/8"-16 Thread Size, 303 Stainless Steel

https://www.mcmaster.com/6438K48

Using TugboatEng's suggestion of a threaded shaft collar with a T-bolt or L-bolt replacing the OEM cap screw with your spacer collar with a topside wingnut might get you a solid spanner free solution. If the operators have a convenient and secure belt tension adjustment mechanism maybe the belt life will be improved.

Your spacer collar protects the threads not in engagement, the wingnut and threaded collar allow quick adjustments without needing tools. Looks pretty promising . . .

This is a good idea. I imagine it having wings on the collar. Adding T bolt, it will be 100% spanner free. Collar sits on another collar to prevent horizontal movement during hand turning, and T bolt locks it up.

I'm thinking root causes - this is coming loose because the grip length between the wing nuts is so very short. Can you a bushing into the plate where the stud passes through, spreading out the wing nuts and adding elasticity? Grip length is an excellent anti-vibration mechanism.

Yeah, indeed that the wing nut grip length is short, and yes to the bushing preventing thread to come in contact with the plate as well. Spreading out wing nuts as in increase the wing grip length? At the moment, it needs to keep the stud or wing nut "locked". Pulling up the spring by turning the wing nut alone is not a problem.

 

[TugboatEng]

You may even be able to use the T-bolt as the handle so you don't need additional handles.

 

[MintJulep]

Grip length is an excellent anti-vibration mechanism.

Actually, it's the bolt elongation that comes with grip length that improves vibration loosening resistance.

With a finger-tightened wing-nut I doubt that you can get enough tension in the threaded rod to make a difference.

I've been thinking about this since the start of this thread, but just found the picture.

 

[3DDave]

MJ, that brings back memories - specifically that if one pulls on the left end of that at all it fractures the plastic. It looks like the FoMoCo part in a car I owned for a while. It arrived broken.

Not sure what the cure for this problem is - the wear is because the threaded rod came loose; if it isn't clamped and is always loose under spring tension it will chew itself and whatever is nearby. I don't like the idea of reaching underneath to manage a jam nut, but a jam nut and a nut tightened with a wrench should be enough to hold the rod from getting loose. But if someone fails to do that there isn't enough tension from the spring, plus the spring adds mass to the end of the rod to cause it to oscillate in rotation and chew itself or neighboring parts up.

I would try to make the spring longer so that it never needs adjustment; idlers on serpentine engine belts with far more pulleys manage to have a one-time windup. If there isn't room vertically, see about a bellcrank to direct a spring in some other direction and eliminate adjustment entirely.

 

[geesaman.d]

Actually, it's the bolt elongation that comes with grip length that improves vibration loosening resistance.

With a finger-tightened wing-nut I doubt that you can get enough tension in the threaded rod to make a difference.

Until we have inelastic materials available, we're kind of saying the same thing. Usually the fastener is the more elastic element but here it's the other way around. So I agree you need to put the elasticity in the clamped section.

Anything that improves the elongation in the bolted joint (how many turns of the wing nut does it take to go from barely-any-torque to full torque? More is better) will make it more resistant to vibration. Spring lock washers can work, belleville washers can work, a high durometer rubber bushing could work, as could enlarging the hole in the sheetmetal and using oversized spacer washers on opposite sides to flex like thrust plates. I guess the best answer depends on how much torque the operator can be expected to apply to the wing nuts. My first attempt would be a pair of meaty bellevilles.

 

[mfgenggear]

When one starts with bad design. It can't be fixed. Belts wear and stretch. So many hours it has to be replaced. And requires preventive maintenance.
I would suggest a handle with a slotted hole, where one pulls up the handle with a bolt and nut. Tighten to torque values. To prevent slipping.
A rod attached to spring and handle as not to become loose.