Reservoir Filters Hoses and Coolers

The primary function of a hydraulic reservoir is to:

Generate system pressure Store fluid, allow deaeration, cooling and contaminant settling Filter fluid under pressure Act as a structural frame

A properly designed hydraulic reservoir should:

Be sealed without any breather Have adequate fluid capacity, baffles and a filtered breather Be as small as possible to save space Operate completely full with no air space

Reservoir baffles are installed to:

Increase pressure in the system Reduce fluid turbulence, promote deaeration and direct return flow away from pump inlet Support the machine cab Increase hose pressure rating

A reservoir breather is used to:

Add dirt to the system Allow air exchange while filtering incoming air Pressurize the reservoir excessively Measure fluid level

Suction strainers are usually located:

In the pressure line to the actuator At or near the pump inlet inside the reservoir In the tank return line At the cylinder rod end

Return line filters are designed to:

Filter oil before it enters the pump inlet Filter oil returning to the reservoir from system components Replace suction strainers Filter air entering the breather

Pressure filters are installed:

On the pump inlet Downstream of the pump to protect sensitive components In the reservoir only Only on low-pressure circuits

Micron rating of a filter refers to:

The filter’s diameter The approximate size of particles the media is designed to capture The filter’s length The number of pleats

A filter with a 10 micron rating generally removes:

Particles 10 mm in size Particles in the range of 10 micrometres and larger as specified by its efficiency Only water Only air bubbles

A filter bypass valve is used so that:

Flow stops when the filter clogs Flow continues around the element to prevent pump starvation when the element is plugged Filter elements never need changing Pressure never changes

Visual or electrical filter clogging indicators are used to:

Measure oil temperature Signal when pressure drop across the element indicates service is required Bleed air from the system Measure reservoir level

Spin-on filter elements are commonly used because they:

Are non-serviceable and must last the life of the machine Are easily replaced as complete assemblies Cannot be used in return lines Require welding to change

A typical hydraulic hose consists of:

Only an inner tube Inner tube, reinforcement layers and outer cover Outer cover only Steel pipe with no reinforcement

The reinforcement in hydraulic hoses may be:

Paper cord only Textile braid, wire braid or wire spiral layers Glass only Unreinforced rubber

Working pressure rating of a hydraulic hose:

Is typically one-quarter of its burst pressure Is the same as its burst pressure Is not important if fittings are tight Can be exceeded if temperature is low

When selecting a replacement hydraulic hose, important information includes:

Hose colour only Inside diameter, pressure rating, temperature range, fluid compatibility and fitting type Length only Outside diameter and paint colour

SAE and ISO hose specifications:

Are unrelated to pressure ratings Provide standardized construction and performance requirements Apply only to automotive fuel lines Are suggestions but never mandatory

Hydraulic hose routing should:

Allow tight bends at the fitting to save space Avoid twisting, excessive bending and rubbing on sharp edges Use the smallest possible bend radius regardless of rating Rest hoses on hot exhaust components

The bend radius of a hose is:

The outside diameter of the hose The minimum radius the hose can be bent without damage as specified by the manufacturer Always the same for all hoses Unrelated to hose life

Hydraulic coolers are installed to:

Increase fluid temperature for cold weather Remove excess heat from the hydraulic fluid Increase system pressure Filter the oil

Air-to-oil coolers typically use:

Engine coolant only Ambient air blown across finned tubes carrying hydraulic oil Only conduction through the frame Water jackets inside the reservoir

Water-to-oil coolers transfer heat by:

Using compressed air Passing hydraulic oil and coolant through separate passages for heat exchange Immersing hoses in water Spraying water directly into the reservoir

If a hydraulic system is running hotter than normal, a parts technician might be asked to supply:

Smaller reservoir Replacement or larger capacity cooler, or cleanable cooler core Lower rated hoses Non-detergent engine oil

Suction lines between reservoir and pump should:

Use small diameter hoses with many fittings Be as short and straight as practical with minimal restrictions Include large numbers of elbows Use high pressure hose only

Return lines to the reservoir should discharge:

Directly into the pump inlet Below the oil level and away from the suction line to minimize aeration Above the oil level to create foam Into the breather

Hose assemblies must be made with:

Matching hose and fittings designed to work together Any fittings that can be forced to fit Household plumbing connectors Unrated clamps

Typical hydraulic hose identification printed on the cover includes:

VIN number of the machine Manufacturer, hose series, size, working pressure and standards Operator’s name Oil change interval

To prevent contamination when changing filter elements, technicians should:

Leave system open to the environment Clean around housings, use proper plugs and follow cleanliness procedures Re-use dirty seals Mix used and new oil

Breather filters on reservoirs should be replaced:

Only when they fall off As recommended by the manufacturer or when restriction indicators show Never, they are lifetime components Only during engine overhaul

A cooler bypass or thermostatic valve may be used to:

Prevent flow when oil is cold or protect against excessive pressure drop through the cooler Increase system pressure indefinitely Replace the main relief valve Stop flow to the reservoir

Hoses located near heat sources should:

Be unshielded to allow cooling Use heat shields or rerouting to prevent overheating and degradation Be painted black only Be replaced with plastic tubing

The ILM Reservoir, Filters, Hoses and Coolers module expects parts technicians to:

Ignore hose and filter specifications Recognize component types, functions and standard ratings when supplying replacements Design new coolers from scratch Mix any hose and fitting brands

A reservoir sight gauge is used to:

Measure pressure Visually check oil level and sometimes temperature Filter contaminants Bleed air

Magnetic drain plugs in reservoirs help to:

Heat the oil Collect ferrous metal particles from the fluid Seal breathers Mix additives

Hose whip or uncontrolled movement after failure is reduced by:

Using lighter hoses Correct clamping, guarding and routing Increasing pressure Removing all supports

Filter beta ratio information indicates:

The filter’s oil capacity Efficiency at removing particles of a specified size Operating temperature range Country of manufacture

A suction strainer should NOT be:

Oversized for low restriction Allowed to become heavily clogged, creating high inlet vacuum Mounted below the fluid level Installed near the pump inlet

Reservoir design should locate the pump suction outlet:

Directly under the return line outlet Away from return inlets to reduce air and sediment carry-over At the highest point in the tank Inside the breather