Skid-Steer Hydraulics

Skid-steer loaders are really nifty machines. Along with their cousins — compact track loaders and multi-track loaders — they have made working in limited spaces much easier in recent decades. Before the skid steer (also known as a skid loader) came into common use back in the late 1950s, bulldozers, skip loaders and graders did all the rough contouring, but much of the fine work had to be done by hand. A similar comparison can be made between the old but still in use “lawn-tractor” type of mower and today’s zero-turn mower, which was a boon to the landscaping industry when it was first introduced in the mid-1970s. Because of the skid steer’s versatility, it has become the most common piece of heavy machinery on the job site today and is the workhorse of the construction industry.

But, as with all machinery, the skid steer is only as dependable as the maintenance it receives. The top two pieces of advice given on every heavy machinery website and on every “showroom floor” is to always follow the operating instructions in the owner’s manual and to always follow the prescribed schedule of regular maintenance. However, just like the human body, skid steers are imperfect, subject to wear and tear, and occasionally suffer breakdowns. Even if you are a religious maintenance zealot, unplanned events still happen, especially as the machine ages.

What we would like to talk about today is what is probably the most common component that is subject to operational issues on the skid loader — the hydraulics system. We will discuss each type of issue, how regular maintenance can often preempt many of those problems and what can be done when “unscheduled maintenance” is occasionally called for.

Problem: The lifting and turning hydraulics seem to be sluggish or not working up to capacity. 

Fixes: The first thing to do is to check the fluid level. If the fluid is low, the machine is trying to do 100% of its job with less than 100% of its resources. Just adding fluid may be all it takes … for now. Check the hydraulic filter. If it is clogged or full of debris, it would be like trying to do heavy exercise with our lungs full of smoke. Also check the hydraulic hoses. If there are any signs of leakage or damage, they will need to be repaired or replaced before any more work is done in order to forestall any further damage to the machine.

Maintenance: Follow the manual’s guidelines for scheduled maintenance. Check the fluid levels. Ensure that the pump belts are not overly worn and are properly tensioned. Depending on the age of the machine, daily checks may be necessary.

Problem: The whole hydraulic system appears to be operating slowly.

Fixes: Eliminate the possibility of an external leak by checking the hoses. An internal leak may be harder to identify. First of all, verify the system’s adjustable settings. Systems with variable displacement pumps use pressure compensators and relief valves to determine fluid flow. These may reduce the power to the components to protect the hydraulics. Ensure that the system is set to the manufacturer’s specifications. If the fluid is exceptionally hot, a more serious internal leak may be indicated. Have the machine serviced right away.

Maintenance: Ensure that the settings are correct during each maintenance procedure. Do not set the pressure relief valve setting too close to the regular operating pressure setting because that would tend to overwork the relief valve and lead to internal leaks.

Problem: There is water in the hydraulic system.

Fixes: If the hydraulic fluid appears to be milky, water has contaminated the system. Although the immediate job can be finished, over time water can reduce the lubricating effect of the fluid and cause damage to metal surfaces. So, it is important to get the machine in for servicing as soon as possible. Completely flush the hydraulic system, clean the reservoir and refill with clean fluid.

Maintenance: Since water contamination can be a recurring problem with hydraulic systems, a couple of best practices can help reduce its reoccurrence. Run the machine regularly in order to keep the operating temperature stable. The heat will remove water from the fluid. Never leave the system exposed to water and make sure that the vent cap is always properly installed.

Problem: The hydraulic system is making knocking noises.

Fixes: Noises are caused by either air contamination (aeration) or a vacuum bubble (cavitation). Neither are an immediate threat to the machine but can cause long-term wear. Schedule maintenance as soon as possible.

Maintenance: Some causes of aeration and cavitation are a collapsed, restricted or poorly designed inlet; clogged or improperly sized reservoir breathers; loose clamps or fittings, porous intake lines, or a low reservoir oil level. Repair or replace all suspect components and ensure that the reservoir is properly filled.

Problem: The fluid has small particles in it.

Fixes: Particulate contamination may be one of the most common problems with skid-steer hydraulic systems because they are always exposed to dirty environments. This, coupled with hurried or careless connections and disconnections, can easily cause contamination. Whereas the filtration system is designed to remove most of the particulates, sometimes the contamination exceeds the filter’s ability to filter. This too may necessitate a clean flush. So, it is necessary to be vigilant when it comes to cleaning. Ultimately, prevention is the best kind of maintenance. 

Maintenance: Whenever disconnecting a fluid line, wipe the couplers down with a clean rag first. And after making a reconnection or close-coupling the system for the day, wipe it down again. Try keeping couplings from being exposed to dust and wind as much as possible when not being used.

A Word About Attachments

Another reason that the skid steer is so popular is its versatility. The machine itself comes in three general sizes: large frame, medium frame and small frame (also known as a mini). A skid loader also may have more available accessories than Barbie and Ken (there are literally dozens)! In addition to hauling heavy loads, a skid steer can be used as a brush cutter, a trencher, a grapple or a forklift, depending on the attachment that is used. Do you need to install long runs of fencing? With an auger attachment, you can dig hundreds of feet of post holes in quick time. Are you removing hundreds of feet of fencing? A tree and post puller will handle that job nicely. You can get attachments that turn a skid loader into a dozer, a stump grinder, a snow blower, a snowplow or a stump bucket. A nice array of landscaping accessories is also available, such as a tiller, a mulcher, a power rake, a spreader and even a sweeper.

Not all of these accessories require hydraulics, but many of them do. Some use high-flow hydraulics; others low-flow. Which one do you need? It depends on the job. For example, if you are going to be doing very heavy-duty work and the attachment has its own motor, you will want to go with high flow. The type of oil to use will also depend on the job. Be sure to do your due diligence when purchasing an attachment.

Another question that arises is whether all attachments are interchangeable. The answer is a qualified yes. Newer machines and accessories are designed to be interchangeable, but some older machines will not take all the newer attachments and vice versa. Make sure you check the compatibility when planning to purchase an accessory or renting one for your older machine.

“Use the right tool for the job” is an old saw that has stood the test of time. Skid steers, compact loaders and multi-loaders, along with all their accessories, have made it possible to have exactly the right tool for virtually any heavy-duty job out there. And regular maintenance, whether scheduled or unscheduled, will ensure that these outstanding tools will last for years, if not decades.