ATV winch switch repair and relubrication-Case Study

ATVs endure harsh conditions, which put the machine and individual components to the test. The electrical components on an ATV are chosen for their durability and often are protected by Ingress Protection (IP) rated enclosures. Given enough time, it’s likely that with enough water, salt, dust, dirt, thermo cycling and UV light exposure (especially with plastics and rubbers), gaps will appear between surfaces, materials will deteriorate and components will age. In the case of this Honda 350 Rancher ATV winch switch manufactured by WARN Industries, the switch was identified as the cause of the winch not working, firstly this was an intermittent fault and then over a period of a few months the winch failed to operate completely. The ATV concerned was a 2001 model, so the machine had coped well for around 20 years before the electrical fault occurred, which is not really a cause for serious complaint. This case study will take the reader through this ATV winch switch repair/cleaning and relubrication.

Specification found online for the winch stated the max current draw under load would probably be 80 Amps but the switch design was discontinued in 2007 so information was sparse. When the switch was disassembled, it was found that the original grease used to lubricate the switch had turned gummy or had dried up, the switch movement was severely impeded. Additionally, the green gunk (verdigris) was covering pretty much all of the copper contact surfaces. Unfortunately the customer did not take a picture before cleaning procedure started, the image below was taken after much of the verdigris removal had already taken place. As this switch is no longer manufactured, the customers goal was reuse all parts so a thorough clean was the first task. The customer used an degreaser and toothbrush to clean the metallic and plastic surfaces such as the springs, steel pivot pins and the switch housing. Also an emery cloth was used to restore the copper contacts back to a untarnished surface:

The presence of verdigris inside the switch clearly shows that he integrity of the switch has been compromised and moisture was able to penetrate into the switch inner workings. That said, the design of the switch is excellent and it has managed to be weatherproof for many years. The hard plastic shell/housing of the switch is made of ABS plastic, there is an elastomer that completely enclosed the switch area and the switch is clamped by a metal bracket which diminishes the ability of moisture from entering the contact area. There are four small holes in the bottom of the switch housing which was covered with a felt-like material, the purpose of these holes could be drainage or ventilation, the felt being used to prevent direct spray intrusion but it’s hard to be sure.

Verdigris is always a challenge for copper contact surfaces operating long term in external environments, even though shielded from direct water penetration, moisture build up or condensation can be enough to cause atmospheric oxidation.

The design of the rocker switch is relatively simplistic but very effective. There is a white ‘actuator block’ which houses a spring inside. Also incorporated into the actuator block is a copper contact which is moved by the rocker switch; the position of the actuator block and in turn the copper contact determine the circuit position/setting. Residue of the original grease was found in most areas of the switch and it seems that the use of a grease was intended primarily to lubricate the electro-mechanical mating of the copper contacts but also possibly the movement of the plastic actuator block agains the ABS switch housing.

Solution

• A synthetic grease based on a Polyalphaolefin oil (PAO) is suitable as there are no super extreme temperatures involved, just normal Summer hot and Winter cold temps.
• A grease specifically formulated for switch applications would be ideal to cope with the light mechanical sliding copper surface interaction and the grease should be dielectric.
• As the switch contact forces are unknown and the switch is old, the finished grease should be soft and use a PAO base oil that has a low kinematic viscosity to ensure a firm mating of conductive surfaces when the switch is operated, ensuring there is no contact ‘aquaplaning’ or other connectivity problems.
• The formulation should use a thickener to help deal with the mechanical lubrication aspect of the task; Lithium soap is a cost effective thickener providing a good level of lubricity, water resistance, temperature and shear stability.
• The switch grease should help protect the copper conductive surfaces resist the verdigris and general environmental contamination, so a formulation containing a rust inhibitor additive would be beneficial.
• There must be no increase in contact resistance across terminations as a result of using the switch grease.
• Plastic compatibility of the switch grease is also an important consideration so that any plastic or elastomer used in the switch design does not swell or crack.

Product Selection

Rheolube 362HT

Rheolube 362HT has been relied upon by the automotive industry for many years to improve electrical switch operation and ensure a long functional life. Perfect for this switch repair application, 362HT is ideally formulated for this light electro-mechanical application and will ensure that contact surfaces are lubricated and protected but will also not impede the effective mating of the conductive surfaces. Additionally the chemistry used in the formulation of Rheolube 362HT is generally considered as being plastic friendly however there can be the small percentage chance that the rust inhibitor additive could cause problems so compatibility testing is normally recommended. Rheolube 362HT is also available in smaller containers at our online shop.

Applying The Grease

The customer obviously focused on applying the grease to the switch contact areas but also decided to coat all the other exposed copper surfaces to avoid verdigris build up everywhere inside the switch housing. The customer correctly did not over coat the contact areas with the grease; common sense applies in terms of how much grease to apply, a thin layer being effective as any excess grease will be mechanically pushed away from the contact area by switch operation, but even though the grease still appears to be between the conductive surfaces, the grease will (in microscopic terms) not be blocking the asperities; in this respect the grease is dielectric and behaves like a connector grease. If the reader is interested in what is happening when the contacts mate in relation to the grease (in microscopic terms), read this article.

A tube of Rheolube 362HT was purchased by the customer and an application aid of some type was used to apply the grease to harder to reach places.

Results

The rocker switch was restored to a level of operation and performance just like new. The winch was able to operated again as normal. The cleaning/restoration and application of Rheolube 362HT ensured that there were no more switch reliability issues and also that it would be highly unlikely that the switch would ever have problems again for the rest of the ATV functional life. The synthetic grease we supply is normally classed as ‘lube for life’ and will extend or exceed the functional life of the hardware.

THE CLEANING AND APPLICATION OF RHEOLUBE 362HT RESTORED THE ROCKER SWITCH TO AN ‘LIKE NEW’ LEVEL OF PERFORMANCe.

It is important to note that normally we would always recommend a compatibility test of the grease vs any plastics or rubbers, before applying the product. When we work with a device manufacturer, this is a standard consideration before moving into volume production, to prevent any possible future warranty issues.

Tubes of Rheolube 362HT can be purchased at our online shop.

Why not take a look at our other articles about switch grease and we also have other case studies that may be of interest.