Front-end loaders carry, lift and deposit loose materials: sand, soil, stone, quarry slag, coal, ore and many other similar loads. The front-end loader needs tremendous power to lift and tilt the bucket located at the end of two long arms. A powered hydraulic system (or circuit) provides the necessary power to lift not only the load, but also the weight of the bucket and arms. When there are problems with the hydraulic power, there are three main components to inspect for trouble: the hydraulic pump, the high-pressure hydraulic lines and the hydraulically actuated piston.
The hydraulic pump on a front-end loader is located either in the forward area of the engine bay or under the driver's compartment. The engine produces electrical power to operate the pump. Hydraulic pumps must be completely sealed and leak free; copious amount of puddle hydraulic fluid could mean the seals around different fitting are no longer tight. Also, the pump assembly has a large canister attached for the hydraulic fluid filter. Changing the filter regularly is a must to maintain optimum power in the hydraulic circuit.
A front-end loader has different movable parts where the hydraulic lines must connect. A combination of hard annealed steel tubing and high-pressure rubber hoses carry the hydraulic fluid to the piston, then low-pressure lines return the fluid to the pump. Make sure all the lines are leak-free. Moving hoses are especially susceptible to chafing getting crimped. Check the hoses for shiny areas where constant chafing is smoothing the surface--these areas can indicate a future trouble spot. Try to pad or protect the hose section from further damage.
The hydraulic lines are connected at each end with stainless steel high-pressure fittings. Make sure all fittings are tight and leak-free. If a fitting does fail, do not try to repair it--it must be replaced. The pressure hydraulic circuits endure almost guarantees any fix will fail quickly.
The hydraulic piston does the work; slow and intermittent piston action is the most obvious indicator of hydraulic circuit problems. Front-end loaders may have up to eight pistons (four on each side) actuating the lift arm, the bucket, a pivot point (so the loaded bucket can turn) and side support legs. Prevent contaminating material from getting into the piston and cylinder assembly with tight seals. If pistons begin to lose responsiveness to controls it could mean a hydraulic pressure loss because of leaky hoses, fittings or seals. Also, any dents or corrosion in the piston and cylinder can cause hindered action. Repair or replace any such damage immediately.