Need the factory reference for your David Brown 780 Selectamatic? This 92-page operator manual covers the 780 Selectamatic, from first-day break-in precautions straight through to full specification data. Inside: a complete walk-through of Selectamatic Controls, live external service operation, differential lock, ballast, wheel width adjustments, and tyre pressures. You get a detailed lubrication chart, a recommended fuels and lubricants guide, linkage settings for both drawbar and Pick-up Hitch, and a specifications section listing every fluid capacity and accessory fitment. The hydraulic pump delivers 5 gal/min at 1800 rpm against a maximum system pressure of 2000 lb/in²; your 3-point linkage is rated to 1600 lb (725 kg) at the link ends. Your machine is down. Get the right numbers, not forum guesses. Bookmarked by section so you jump straight to what you need; one download and it opens on any device.
What's Inside This David Brown 780 Selectamatic, 780 Selectamatic Livedrive Operator Manual
| System | Pages | Key Topics |
|---|---|---|
| Precautions with a New Tractor | 4 | Engine Oil, Filter Element, Transmission Oil, Hydraulic Filter Element, Transmission Gearbox Flush, Wire Mesh Screen, Nylon Filter, Hydraulic By-Pass Valve Assembly |
| Operation | 5-38 | Starting the Engine, Controls, Selectamatic Controls, Operation of Services, Operation of Live External Services, Differential Lock, Ballast, Wheel Width Adjustments |
| Regular Maintenance | 39-51 | Lubrication Chart, Recommended Fuel Oil and Lubricants |
| Servicing Information | 52-77 | Index to Servicing Information, Wiring Diagram |
| Specification and Data | 78-92 | Capacities, Accessories, Abbreviations |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Maximum hydraulic system pressure | 2000 lb/in² (140 kg/cm²) | p. 85 |
| Hydraulic pump delivery | 5 gal/min (6 U.S. gal/min) (22-3 litres/min) at 1800 rev/min engine | p. 85 |
| Injectors pressure setting | 175 atmospheres (180 kg/cm²) | p. 81 |
| Maximum load at the end of the links | 1600 lb (725 kg) | p. 85 |
| Engine Oil Capacity | 6.25 L | p. 84 |
| Transmission Oil Capacity | 22.7 L | p. 84 |
| Fuel Tank Capacity | 36.4 L | p. 84 |
| Cooling System Capacity | 9.1 L | p. 84 |
| Rated Engine Speed | 1800 rev/min | p. 80 |
| Standard PTO Speed (at 1800 rev/min engine) | 532 rev/min | p. 85 |
| Valve Clearance (cold, inlet) | 0.010 in. (0.25 mm) | p. 80 |
| Cylinder Head Torque | 90 lb ft (12.5 kg m) | p. 65 |
David Brown 780 Selectamatic, 780 Selectamatic Livedrive Common Problems This Manual Covers
David Brown 780 Selectamatic lift arms stay in the down position and will not lift heavy implements. p. 85
Verify your implement does not exceed the maximum load of 1600 lb (725 kg) at the end of the links as listed on page 85. Check the hydraulic by-pass valve assembly for stuck debris. Drain and refill the transmission with exactly 22.7 L of clean fluid.
Manual Section: Specification and DataEngine cranks over but refuses to start after fuel returns to the tank or changing filters. p. 81
Bleed the fuel system completely to remove trapped air. Inspect the injectors and verify the pressure setting is at 175 atmospheres (180 kg/cm2) as specified on page 81. Clean the injector pump connections and ensure fresh diesel is reaching the cylinders.
Manual Section: Specification and DataTransmission filter warning lamp flashes continuously while operating in cold weather at high engine speeds. p. 8
Check the operator controls layout on page 8 to confirm the warning light meaning. Inspect the wire mesh screen and nylon filter for blockages. Warm up the tractor and add fluid if needed to reach the total transmission oil capacity of 22.7 L.
Manual Section: OperationPower take-off cannot be freed and gears grind loudly when attempting to engage the live drive. p. 72
Adjust the linkage stop until the clutch free-play measures exactly 3/4 to 1 in. (1.9 to 2.5 cm) as shown on page 72. Tighten the locknut securely after setting the gap. Test the pedal travel to ensure smooth disengagement before operating.
Manual Section: Servicing InformationFrequently Asked Questions
How to reset the fuel system on a David Brown 780 Selectamatic?
To reset the fuel system, first fill the tank with a minimum of 2 gallons (9 litres) of fuel. Then, clean the outside of the filters, remove plug G, slacken union H, and operate the fuel pump, tightening in order G then H as fuel appears. Continue by slackening plug J on the injection pump, priming until air is expelled, then tightening J, and repeat for plug K. Finally, slacken the high pressure pipes at the nozzle end, operate the starter until fuel is ejected, then tighten the pipes and run the engine to check for leaks.
What is the torque specification for the main engine bolts on a David Brown 780?
The torque specification for the cylinder head bolts is 90 lb ft (12.5 kg m). It is important to follow the tightening sequence shown in Fig. 3/15 and check valve clearances after tightening the head.
What are the replacement specifications for Three-way valve?
Replacement units for the 3-way hydraulic valve are available as accessories. Part number U1230 is for the valve with pipe and coupling, while U1229 is for the valve less pipe and coupling.
How do you fix david Brown 780 Selectamatic lift arms stay in the down position and will not lift heavy implements?
Verify your implement does not exceed the maximum load of 1600 lb (725 kg) at the end of the links as listed on page 85. Check the hydraulic by-pass valve assembly for stuck debris. Drain and refill the transmission with exactly 22.7 L of clean fluid.
What do I get after purchasing this David Brown 780 Selectamatic, 780?
Instant PDF download. You get the full 92-page searchable Operator Manual immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Am I able to print pages from this David Brown 780 Selectamatic, 780?
Yes. The PDF has no DRM restrictions, so print any page or section you need for your shop. Works with any standard printer.
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