ESP 19
4-6
4-4 HYDRAULIC SYSTEM
Hydraulic system maintenance varies by the amount of use and the environment in
which the lift vehicle is used. Keeping the hydraulic oil clean and the reservoir properly
filled will help prevent possible damage to the system.
Hydraulic System Inspection
Check all hydraulic hoses and fittings for leaks and damage daily. Tighten or replace as
necessary to prevent hydraulic oil loss.
Fluid Check and Replacement
With the platform in its lowest position, the hydraulic oil level should be at the
MAXIMUM level mark (1-1/2 in. from top of reservoir).
The reservoir is initially filled with Energol HLP-HD46 (BP Oil); a high grade, non-
foaming hydraulic oil. This oil is recommended for use in climatic temperatures as low
as -20°F/-29°C. Dextron Automatic Transmission Fluid Type A is recommended for use
in temperatures as low as -40°F/-40°C.
If either of these oils is not available, a good grade SAE 10W hydraulic oil may be used
where the minimum climatic temperature is above 32°F/0°C. An SAE 5W hydraulic oil
may be used where temperatures are as low as 0°F/-18°C.
Do not mix different hydraulic oils. Clean the reservoir and sump strainer and replace
the hydraulic oil at least once a year. Clean the reservoir and sump strainer and replace
the oil whenever contamination is suspected.
Hydraulic System Air Bleeding Procedure
Delayed response or uneven movement of the hydraulic cylinder may indicate trapped
air in the hydraulic oil.
NOTE: Whenever the upper control box emergency stop pushbutton is engaged,
lift operation remains enabled at the lower control box. However, the
UP
or
DOWN lift motion will be intermittent. Intermittent lift motion should
not be mistaken as trapped air in the hydraulic system.
Perform the following procedure to bleed trapped air from the hydraulic system.
1. Fill the reservoir to the
MAXIMUM level with the proper hydraulic fluid.
2. Fully raise the lift platform.
3. Lower the lift platform to allow oil with entrapped air to return to the reservoir.
Be careful not to overflow the hydraulic reservoir.
4. Leave the lift platform down and the lift vehicle at rest for 10 to 15 minutes
while air escapes the hydraulic oil.
5. Repeat steps 2 through 4 as needed. Each time the platform is lowered, refill
the reservoir to prevent pumping more air into the hydraulic cylinder.
