FAQ Couplings

Indicator lamp

We have discovered that on some vehicles the remote indicator lamp does not go off after coupling. This could be because the signal pin on the mechanism is not going in properly by itself. You can easily fix this yourself. Use a screwdriver to press out the locking key, and then give the top of the sensor a rub with a piece of emery cloth before replacing it. This fault has been rectified in production a long time ago, but a small number of couplings were put on the market before we became aware of the problem.

It's all about safety!

This time it’s all about safety. Despite clear instructions, we see way too many cases of wrongly installed cotter pins (the one locking the castellated nut on the coupling) in conjunction with servicing or repairs. A correct installation is very important, especially for rubber-suspended couplings that move around a lot. On the production line, we have therefore now replaced the cotter pin with a locking screw. Make sure you get the pin substituted for the screw (part no. 09-125000) at the next service – in addition to being safer, it is also much easier to install and remove. This concerns the VBG 760, 8500 and the 8040.

    

Protective Insert for VBG 750V/795V

A lot of people have been asking whether there is a protective insert for the 750 and 795 couplings, because other models have them. I am pleased to announce that it is now possible to order one (part number 09-014500). If you missed that news item, now you know! The protective insert is most useful during the winter, when road dirt is extremely aggressive. A protective insert in the coupling when it is not being used significantly increases its service life. You can count on it being worthwhile, so I hope we see a lot more people using the protective insert out on the roads in the future.

Tips from the doctor:

I’ve heard from colleagues that it’s not a good idea to paint couplings. Is this true?

Yes, your colleagues are absolutely right! First of all it is not necessary, because on delivery the couplings have been treated with a very abrasion resistant powder coating, applied over a uniquely powerful corrosion protection primer. Additional painting can, depending on the type of paint, weaken the underlying layers and this can have a negative effect on the corrosion protection. Secondly, additional painting can have an adverse effect on functionality because the paint seeps in where it is not wanted. The signal pin can start to jam, and important information can be painted over etc. If absolutely must change the colour of the coupling we recommend very careful masking of all moving parts, labels and decals.

Some customers feel that the coupling mouth on the VBG 750V and 795V couplings do not sit firmly, and can cause abnormal noise sometimes. Can we do anything about this?

The new design means that the coupling mouth is now replaceable. It is held in place by the upper and lower jaw bushings, so that it can easily be replaced if it is damaged. The updated couplings (which you can read more about on page 1) have a new coupling mouth design with closer tolerances, which means that together with the modified bushings they are more securely fixed in the jaw. In other words the solution is to change to the new coupling mouth and fit the new bushings. (The new bushings are also included in the complete mechanism).

What is the lock pin actually for?

The signal and lock pin has twin functions. Firstly it is a mechanical indication of the position of the coupling bolt. Pin in = coupling closed and locked.
Pin out = coupling open or unsecured. The position of the pin can be checked both visually or by touch. Secondly, the pin is another mechanical locking of the coupling in closed position (the first is the double lock arms inside the mechanism). You know that you always have to check that the pin is completely in before you drive off.

I renovated my VBG 620 coupling and changed both the mechanism, lower jaw bushing and wear ring in the drawbar eye. But it still seems to rattle when I’m driving with a trailer. Have I missed something?

The upper jaw bushing is probably also worn. The vertical play for the drawbar eye then becomes excessive. Normally you have to replace the upper jaw bushing during every other renovation, but if you are driving with a trailer you change it every time you change the mechanism.
This applies to all the VBG 620, 623 and 6000 couplings.

I am going to replace my coupling, but I’m not sure if it’s 620 or a 623. How can I tell the difference? And does it mean anything?

You can’t see the main difference, but it is there and it’s very important. It’s the type of material quality in the coupling jaw. The 623 is stronger. If you change to the wrong one the weaker 620 will not handle the same coupling class. Start by looking for the type plate on the coupling jaw (not on the mechanism). It will tell you exactly what you have. If it’s gone, compare the length of the jaws. If the upper is shorter than the lower you’ve got a 620, if they are the same length it’s the strong one, the 623.

When I’m coupling it’s difficult to get up the mechanism, because it’s so stiff. You would have thought that it could at least stay in open position, but it doesn’t do that either. Why is it like this?

Your problem is probably something as simple as the mechanism being full of grease and dirt. Give it a good wash with environment-friendly degreasing agent. Put a bucket under it so it doesn’t run into the local environment. Lubricate the inside of the mechanism with a thin oil, such as VBG Mechanical Oil. Couple and uncouple a few times. Continue coupling, lubricating, coupling until no more dirt runs out. If you lubricate the mechanism every week with a thin oil, you will probably have solved the problem.

My 760 coupling seem to have a tendency to have too much play after only a few years of driving, so that the trailer jerks. What should I do?

It's a piece of cake. We’ve now increased the tensioning interval for the rubber element down to 17 mm from the earlier 19-21 mm. If you tension it to this you’ll get a tighter coupling with less risk of play, which improves compliancy. This will also reduce any tendency for the trailer to seem to jerk. Important! The cotter must be fully down in the groove on the castellated nut. If necessary, place a 6 mm washer under the nut. Remember to lock round the turrets on the nut, not up and down along it.