Hydraulics & Controls
1.5 hours
Learning Objectives
- •Describe the hydraulic system that powers the lift and tilt functions of a forklift
- •Explain the function of the lift, tilt, and (where equipped) reach and side-shift controls
- •Explain safe use of mast tilt when picking up, carrying, and placing loads
- •Identify hydraulic warning signs that require taking a truck out of service
Topics Covered
- •Hydraulic system: pump, reservoir, control valves, lift cylinder(s), and tilt cylinders
- •Lift control: raises and lowers the carriage; lower smoothly, never let a load free-fall
- •Tilt control: tilts the mast forward and back; back-tilt cradles the load, forward-tilt is used only to pick up or set down
- •Auxiliary functions: side-shift, fork positioners, reach mechanism, attachment controls
- •Travel with the load tilted back and the forks low — only as high as needed to clear the surface
- •Forward-tilting an elevated load moves the load center out and can tip the truck — keep tilt minimal when elevated
- •Control discipline: operate hydraulics smoothly; never use lift or tilt with anyone near the load
- •Hydraulic leaks, slow or jerky lift, mast drift, and unusual noise are out-of-service conditions
- •Park procedure: forks flat on the ground, controls neutral, brake set, key off
Resources
Self-Check Questions
Question 1: You have just picked up a palletized load. Before traveling, how should the mast be positioned?
- A. Tilted fully forward to keep the load visible
- B. Tilted back to cradle the load, with the forks raised only as high as needed to clear the surface(correct)
- C. Tilted back and raised as high as the mast will go
- D. Vertical with the load resting on the ground
Show Explanation
Explanation:
Travel with the mast tilted back to cradle the load and the forks low — only high enough to clear the ground. A low, back-tilted load keeps the center of gravity low and inside the stability triangle. Exam tip: high loads and forward tilt while traveling are classic tipover causes.
Question 2: Why is it dangerous to tilt the mast forward when a load is raised high?
- A. It drains the hydraulic reservoir
- B. It moves the load center forward and raises the tipping moment, which can tip the truck forward(correct)
- C. It locks the steering
- D. It has no real effect as long as the load is under rated capacity
Show Explanation
Explanation:
Forward-tilting an elevated load pushes the load center out away from the front wheels, increasing the load moment. Combined with the higher center of gravity, this can tip the truck forward. Forward tilt at height should be minimal and done only to place a load.
Question 3: During a pre-shift check the mast slowly drifts down on its own when raised and the controls are in neutral. What does this indicate?
- A. Normal behavior for any forklift
- B. A hydraulic problem (e.g., cylinder or valve leakage) — the truck should be taken out of service(correct)
- C. The battery needs charging
- D. The forks are too long
Show Explanation
Explanation:
Mast drift means the hydraulic system is not holding pressure — a leaking cylinder seal or control valve. A load could settle or drop unexpectedly. This is an out-of-service condition until repaired.
Question 4: What is the correct way to lower a load with the lift control?
- A. Release the control fully so the load free-falls quickly
- B. Lower it smoothly and under control(correct)
- C. Bounce the control to ease the load down
- D. Lower it only while the truck is moving
Show Explanation
Explanation:
Loads should be lowered smoothly and under control. Letting a load free-fall or bouncing the control shock-loads the mast and chains and can cause the load to shift or fall.
Question 5: A forklift has a visible hydraulic fluid leak dripping from a hose fitting. What is the correct action?
- A. Top off the reservoir and keep working
- B. Wrap the fitting with tape and continue the shift
- C. Take the truck out of service and report the defect for repair(correct)
- D. Use the truck only for unloaded travel
Show Explanation
Explanation:
OSHA requires that a truck found defective or unsafe be taken out of service until repaired. A hydraulic leak can lead to loss of lift or tilt control and is a fire hazard near hot components — report it and tag it out.
Question 6: When parking a forklift at the end of a task, the operator should:
- A. Leave the forks raised so they are ready for the next load
- B. Lower the forks flat to the ground, put controls in neutral, set the brake, and turn the key off(correct)
- C. Leave it running with the brake off so it warms up
- D. Tilt the mast fully forward
Show Explanation
Explanation:
Proper park procedure is forks fully lowered flat on the ground, controls neutralized, parking brake set, and the engine/key off. Lowering the forks removes the risk of someone walking into raised tines and prevents hydraulic drift.