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Improve the durability of your impact wrench by lubricating the airline AND impact mechanism

December 17, 2019

Tire changing Energy Impact Wrenches Tools

Has your pneumatic impact wrench started to become unreliable, not perform as it should or suddenly stopped working? One of the most common reasons for lack of durability and premature tool failure is inadequate lubrication – and not just of the motor, but also the impact mechanism.

Improve the durability of your impact wrench by lubricating the airline AND impact mechanism

It’s well known that regular maintenance is vital to make sure your tool is performing at its best. In the same way that you keep the oil levels topped up in your car, it’s important to regularly check the oil and grease in your tool. A little maintenance can go a long way towards improving its durability and longevity.

In this blog we’ll look at the two different areas for lubrication and explain how you can maintain your impact wrench properly to ensure that it keeps delivering excellent performance over a long lifetime. We’ll also discuss how often you should lubricate your air tools, and what type of oil you should use so you can make sure you’re working as productively as possible.

Which parts of an impact wrench need lubricating?

When it comes to lubrication, there are two parts of the wrench to consider:
a. The motor
b. The impact mechanism

expert article - lubrication impact wrench - 2 separated lubrications drawing

The two parts of an impact wrench that need lubricating: the motor and the impact mechanism.

You may be aware that the motor needs regular lubrication, but did you know that the impact mechanism needs lubrication too? Both systems are independent from one another, and therefore must be lubricated separately. The motor is lubricated by a specific airline lubricator that you add in the FRL or directly at the air inlet (at the tool). Whereas the impact mechanism is lubricated in one of two ways depending on the system the tool uses. These are:

  • Grease impact mechanism 
  • Oil bath impact mechanism

Understanding the two types of lubrication systems for the impact mechanism

Lubricating the impact mechanism is vital to minimize the friction between the impact contact points of the anvil and hammer, and therefore keeps the wrench running in excellent condition. Let’s look at these two systems in greater detail:

1. Grease system:

Impact mechanism with grease lubrication

Impact mechanism with grease lubrication

In this system grease is applied only on the contact points between the anvil and hammer to prevent friction between them.

expert article - lubrication - focus impact mechanism grease WARNING

An impact wrench mechanism with a grease system needs regular grease replenishment.

However, over time, the grease will move from the contact points to the outside of the hammer (due to principles of inertia) and so will become absent in this critical area. As a result, there will be increased friction, and heat, and the tool will ultimately stop working. It needs regular grease replenishment.

2. Oil bath system:

expert article - lubrication - focus impact mechanism oil bath

Impact mechanism with oil lubrication

In a tool which uses oil bath system, the entire front part of the impact wrench is submerged in oil. There is no question as to whether the oil is present or not, because it surrounds the whole system.

One advantage is that lubrication is always present on the contact points, and therefore it requires less maintenance. Maintenance can be trickier, but, with the right tips and pieces of advice, it become very easy to do – as outlined below.

How to lubricate the impact mechanism of an impact wrench properly?

1. Grease system:

To lubricate the impact mechanism properly, we recommend you open the tool and add grease carefully with your hands or a brush on the critical contact points: the anvil (area in contact with hammer) and in the hammer’s inner area.

Most pneumatic tools have multiple grease fittings, and if it isn’t possible to lubricate the impact mechanism as described above, it is sometimes possible to add grease through these holes. If you aren't sure where they are, check your manual or ask your service provided. Don’t forget to remove the old grease before adding the new one!

Tool operating conditions:  Tool frequency of use : low Tool frequency of use: high
Low Around 6 months Around 3 months
High Around 3 months Around 1 month

2. Oil bath system:

To change the oil, you have to open the tool carefully, drain the used oil and dispose of it appropriately, and then replace it with a new oil.
It is imperative that you use oil, which is only suitable for impact systems, for example oil type SAE30.

Note: this is different oil from oil used in air lubrication.

Tool operating conditions:  Tool frequency of use : low Tool frequency of use: high
Low Around 12months Around 6 months
High Around 6 months Around 2 months
Antoine Tourneux - expert head zoom

The frequency at which lubrication checks should be carried out depends on your usage and maintenance schedule, and we recommend following manufacturers’ advice here.

Antoine Tourneux , Global Product Marketing Manager, Vehicle Service Air Tools, at Chicago Pneumatic

Note: regardless of the lubrication type, only use cleaners and grease that have been recommended by the manufacturer. Double check with the tool manual or your service provider if you are not sure.

What are the consequences of not lubricating correctly?

If the lubrication is applied correctly and frequently, the durability of a tool with a grease mechanism and an oil batch mechanism will be very similar. However, most of the time, grease is not added often enough, and the impact mechanism durability decreases considerably.
An impact wrench that has not been lubricated properly will operate with a lower power output, and if the tool is continually used when starved of grease, the internal components will wear down and the tool will not last nearly as long as it could.

Antoine Tourneux - expert head zoom

Improve the durability of your air tool by regularly lubricating the motor and impact mechanism.

Antoine Tourneux , Global Product Marketing Manager, Vehicle Service Air Tools, at Chicago Pneumatic