An indicator light flickers on mid-shift and nobody on site can tell you what it means. That question is exactly why the Lull 644D-34 operator manual PDF exists: 30 pages of factory operating guidance for this rough terrain forklift, published under OEM ID 68998A. Reading the sample load chart gets its own section, walking you through the vertical and horizontal scales, boom angle arcs, and load areas before you ever pick anything up. Safety fills roughly a third of the book, from ROPS and FOPS to refueling and machine stability, with gauges, indicator lights, steer modes, and joystick controls explained right after. Charge the accumulator to 685 to 715 PSI of nitrogen, and expect 55 to 60 PSI of engine oil pressure at speed. Some days it is just you and the machine, with no one left to ask. Bookmarks and a real text layer put the load chart or lube schedule one click away.
What's Inside This Lull 644D-34 Operator Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 4 | Warranty Registration, Pre-Delivery Inspection, Operator Manual, Engine Manual |
| Safety | 5-11 | Safety Standard, Decals, ROPS, FOPS, Refueling Safety, Machine Stability |
| Instruments and Controls | 12-19 | Gauges, Indicator Lights, Ignition Switch, Shift Selector, Steer Mode Selector, Joystick Controls |
| Before Operating the Machine | 20-21 | Equipment Inspection, Work Area Inspection, Work Planning, Protective Clothing, Mount and Dismount Procedures |
| General Operating Procedures | 22-25 | Starting Procedures, Shutdown Procedures, Traveling, Load Lifting, Load Transport, Personnel Lifting |
| Service/Lubrication Schedule Model 644D-34 | 26-27 | System Capacities, Fluid Specifications, Lubrication Schedule, Maintenance Intervals |
| Sample Load Chart | 28-30 | Vertical Scale, Horizontal Scale, Boom Angle Scale, Lettered Arcs, Load Areas, Transaction Area |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Accumulator Nitrogen Precharge | 685–715 PSI | p. 23 |
| Planetary Hub Capacity (Each) | 34 OZ | p. 27 |
| Tire Pressure | 65 PSI | p. 27 |
| Normal Engine Oil Pressure | 55-60 PSI | p. 12 |
| Normal Operating Voltage | 14.5-15 volts | p. 12 |
| Normal Engine Water Temperature | 180-185 °F | p. 12 |
Lull 644D-34 Common Problems This Manual Covers
Lull 644D-34 hydraulics bang and surge every few seconds at idle with no control input
Check hydraulic fluid level and condition before anything else; foamy or milky oil means the pump is pulling air. Verify the accumulator nitrogen precharge holds 685 to 715 PSI, the spec listed on page 23. If the fluid looks dark or smells burnt, change it and the filters per the maintenance schedule on page 27.
Manual Section: Hydraulic System p. 27Forward drive feels weak and machine struggles under load when backing onto a trailer
Check transmission oil level with the engine idling and fluid warm. Verify all four tires hold 65 PSI; soft tires drag hard on trailer ramps. Watch the transmission oil temperature gauge covered on page 12, and if it runs hot, idle in neutral until it cools. Change fluid and filter per the schedule on page 27.
Manual Section: Transmission p. 27Engine water temperature gauge climbs above normal range during long lift cycles in hot weather
Verify the gauge against the normal operating range of 180 to 185 °F, explained on page 12. If it climbs higher, ease off the load and let the engine cool at fast idle; never remove the cap hot. Check coolant level once cool and clean debris from the radiator per the cooling system maintenance on page 27.
Manual Section: Engine Water Temperature p. 12Engine oil pressure gauge reads low or drops suddenly at full operating temperature
Check the gauge reading against the normal range of 55 to 60 PSI described on page 12, and shut the engine down right away if pressure falls below it. Inspect the dipstick on level ground, then fill with the oil grade listed in the fluid specifications on page 26 before restarting.
Manual Section: Engine Oil Pressure p. 12Voltmeter reads below normal after startup and battery slowly goes dead overnight
Check the voltmeter with the engine running; a healthy charging system holds 14.5 to 15 volts, per the gauge descriptions on page 12. Clean the battery terminals and cable ends, then inspect alternator belt tension during the pre-operation equipment inspection on page 20. Test voltage again after a full warmup.
Manual Section: Instruments and Controls p. 12Frequently Asked Questions
What is the normal engine oil operating pressure on the Lull 644D-34 rough terrain forklift?
The normal operating pressure for the engine oil is between 55 and 60 PSI. The gauge on the instrument panel registers from 0 to 80 PSI. p. 12
What is the hydraulic reservoir capacity on the Lull 644D-34 rough terrain forklift?
The hydraulic reservoir has a capacity of 33.8 gallons. p. 27
How often should the boom wear pads and slide areas be lubricated?
The boom wear pads and slide areas should be lubricated monthly using EP lithium-based grease or a dry-film lubricant. p. 26
What is the required tire pressure for the 13.00 x 24 12-ply tires on a Lull 644D-34 forklift?
The required tire pressure for the 13.00 x 24 12-ply tires is 65 PSI. p. 27
What is the recommended engine coolant capacity for the Lull 644D-34?
The cooling system capacity for the machine is 18 quarts. p. 27
Is this Lull 644D-34 Operator Manual a digital download?
This is a 30-page searchable PDF ready for immediate download. Works on any device, so pull it up on your phone while you're under the hood. No shipping, no waiting.
Can I print just the pages I need from this Lull 644D-34 manual?
Yes, printing is unrestricted: a single page, a chapter, or the lot, on letter or A4.
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