Question 1

INFORMATION ON LOADERS

Accepted Answer

Not all David Brown front loaders are compatible with every tractor model. Each loader is identified by a combination of letters and numbers found on an identification plate, typically located on the left underside of the loader frame.

For example:
LF7
L = Loader
F = Front
7 = Designed for 770 & 780 tractors

Other common designations include:
LF8 – for 880 tractors
LF9 – for 990, 995, 996 tractors
LF12 – for the 1200–1412 range

Loader Types
LF loaders: Standard duty, single-acting rams
LH loaders: Heavy duty, single-acting rams
LS (Super Loaders): Double-acting rams

With the introduction of the 90 Series tractors, early models could still accept some LF loaders. However, these were soon replaced by the more robust H-type loaders:
FD90 – Standard duty
GD90 – General duty
HD90 – Heavy duty

These were fixed-frame loaders. Later, QD (Quick Detach) loaders were introduced, featuring a detachable design. When Case IH took over and introduced red livery, these loaders were rebranded as:
L1000, L1100, L1200, L1500 – where the number refers to the lifting capacity in kilograms

Hydraulics & Controls
Early loaders used a single crowd ram; later QD and HD loaders had twin rams.
QD loaders introduced improved hydraulic connections with a block of quick-release couplings integrated into the loader bracket. Operation was cable-controlled via the cab-mounted spool valve system.
Earlier loaders connected to the tractor’s hydraulic system via a 3-way valve, using the standard hydraulic lever latched in the "select" position.

Due to HSE regulations, exposed oil pipes within the cab became prohibited. This led to the adoption of external pipe systems and quick couplers. Before factory systems were standardised, some operators used aftermarket quick-release kits (e.g. by Slewtic).

Optional Loader Accessories
Levelling bar (keeps two points of attachment parallel at all lift heights)
Pallet fork assembly
Quick-release system for bucket/fork attachments
Loader stand (for storage when removed)

Inspection Tips Before Purchase
Check hydraulic rams for rust, pitting, or damage to chrome surfaces
Inspect seals for oil leaks
Examine hydraulic hoses for wear or cracking
Pay attention to bracket and pin hole wear, especially at mounting points - pin holes typically wear more than the pins themselves

With thanks to Powerrabbit for the original detailed overview.

Question 2

BLEEDING THE FUEL SYSTEM

Accepted Answer

Preliminary Checks

Fuel supply: Ensure the tank is adequately filled – running out of fuel is a common reason for needing to bleed the system.
Manual: Keep your tractor manual nearby for reference. Diagrams for typical fuel systems with in-line and rotary (CAV) pumps are included for guidance.

Bleeding Procedure – 4 and 6 Cylinder Engines

1. Prime the system using the fuel lift pump

Begin by hand-operating the fuel lift pump.
Open the bleed screws on top of the fuel filter housings one at a time, starting with the one closest to the fuel tank.
Pump until fuel flows out without air bubbles.
Tighten the screws gently – the housings are aluminium and easily damaged.

2. Bleed the injection pump

Open the bleed screws on the injection pump.
Continue priming by hand using the lift pump.
Since the injection pump is on the opposite side of the engine, it may be difficult to see – get assistance if possible.
Once air-free fuel flows from both screws, tighten them.

3. Bleed between the injection pump and injectors

Loosen the fuel delivery pipe nuts on one or two injectors (two adjacent ones for 6-cylinder engines).
A few turns will do – just enough to lift the pipe off its seat so fuel and air can escape.

4. Start the engine

Use the starter to crank the engine; if cold, use the thermostart.
Once the engine begins to fire:
For 4-cylinder: tighten the loosened injector pipe and crank again until it starts. The remaining cylinders should follow.
For 6-cylinder: tighten one injector pipe when it begins to fire, then tighten the other as it continues running. The engine should smooth out as all cylinders fire.

5. Inspect for leaks

Let the engine run while checking all pipes and bleed screws for leaks.
Reinspect them during the next 10 hours of operation.

Bleeding Procedure – 3 Cylinder Engines
3-cylinder engines typically require a simpler process:

1. Clean the sediment bowl

Remove and clean the bowl and gauze.
Inspect or replace the rubber seal if necessary.

2. Reassemble and refill

Refit the sediment bowl and screw up the yoke loosely.
Allow it to fill and overflow, then tighten it and clean up any spilled fuel.

3. Service the fuel filters

Remove both fuel filters, clean the bowls, and fit new filters with fresh ‘O’ rings and seals.
Locate the 9/16" hex head on the filter housing (near the tank side); this bleeds both filters.
Loosen this screw and pump the lift pump by hand until fuel flows without air.
While pumping, tighten the bleed screw as fuel is expelled.

4. Final steps

Wipe down the system.
The engine should now start without bleeding the injection pump.
Run at approximately 1100 RPM for five minutes, then inspect for leaks.

Reference Diagrams

Example A: 4-cylinder fuel system with in-line injection pump
Example B: System with a rotary (CAV) pump

(Refer to manual or schematic diagrams as needed.)

Question 3

NUTS, BOLTS & SPANNERS

Question 4

QUICK CHECK HYDRAULIC FAULT FINDING

Accepted Answer

This guide is adapted from a David Brown (Canada) service bulletin and is primarily based on DB 990 A & B models, though other models are referenced. It is not a comprehensive manual, but it may help in diagnosing hydraulic faults. Please email admin with any questions or feedback.

Thanks to Ivan (DB 770, DB 880) for supplying the information.

Initial Checks

Remove Covers

Take off the small top cover above the valve chest (on the axle) and the rear cover on the right-hand ramshaft bracket.

Start the Engine

From behind the tractor, observe the rear opening (pipe #915339).
In External Services position, oil should flow steadily from the pipe if the pump is working.

Operate the Quadrant Lever

Pull the lever into the Select position.
If oil flow stops, the bypass valve has seated correctly — system is functioning up to this point.
If oil continues flowing, the bypass valve has not seated.

Momentarily switch to Height position (with links down) to check if the abutment plate is obstructing the spool valve. Then return to External Services.

Possible Causes of Bypass Valve Not Seating

Spool valve not fully dropping into lift position
Spool valve sticking in its sleeve
Dirt in the bypass screen or blocked .020" washer hole
Tight spot in valve movement – may need lapping with jeweller’s rouge through full rotation

Hold Valve Check

With the quadrant still in Select and bypass valve seated, look forward through top plate #910182.
At ~1000 RPM, if a jet of oil emerges from the indicated slot, the hold valve is not seating.

Possible causes:

Tip hole of the hold valve is blocked
Tight spot in valve or bore – may require lapping
Shock load relief valve (item 10, p.54) may be leaking — visible from the top of the valve chest

Additional Leak Checks

Remove Plate #910860 from front of quadrant housing

Lever in Select, inspect with good lighting for leaks:

From plugs under hold and bypass valves (held with circlips)
From O-rings (item 32, p.54) between pipe #915687 and valve chest
From pipe #915687 itself – check for cracks or splits

Check 3-Point Hitch Cylinder (#910107)

If no visible external leaks, test pressure at the cylinder inlet using a gauge.
Low or no pressure? Possible leak or split in pipe #928511 or a loose union.

Pump Pressure Testing

All models (except 1200)

Test at item #25 using a pressure gauge and blanking plug #961977 (see p.23 of the service manual).
This isolates the system down to the pump, relief valve, and pipe #915684 (with O-rings).

Model 1200

Quick test via stack valve.
Full procedure is detailed on page H5 of the special tools list.

Important System Notes

In External Services, the quadrant lever and abutment plate are active.
The sensing unit, cable, sensing pushrod, cam, and cam-operated pushrod are not part of the system in this mode.

Common Fault Scenarios

Scenario 1:

Lever in Select/Height/Depth, main relief valve blows
Implement does not lift
No oil pressure at cylinder inlet (#910107)
When moved to Drop, the valve stops blowing
Likely Cause:
Non-return valve seal has blown out – valve chest replacement required

Scenario 2:

Lever in Lift, implement raises fully but continues to blow relief valve
In Hold, pump keeps running (relief valve continues to blow)
On stopping engine and selecting Drop, implement remains raised
Likely Cause:
TCU valve seat has blown out – prevents pressure release
Valve chest replacement typically required

This guide provides a structured method for tracing hydraulic issues. While not exhaustive, it offers practical diagnostics for common faults.

Question 5

TIPS ON FITTING DECALS

Accepted Answer

Before Renovation
Before stripping the paint from your bonnet, take time to measure and record the exact position of the original stickers. This will ensure accurate placement of the new ones. Keep your notes somewhere safe for future reference.

Removing Old Stickers
A hot air gun is often the easiest way to remove existing stickers. Apply gentle heat to soften the adhesive without damaging the paint beneath. After removal, use an appropriate surface cleaner to eliminate any remaining adhesive residue.

Surface Preparation
Proper preparation is key to a professional, long-lasting finish.

Stickers are usually applied after a repaint or full renovation.
Ensure any fresh paint, particularly enamel, is fully cured before applying stickers.
The surface must be smooth, dust-free, and free from grease or solvents—any imperfections will show through the vinyl.

Ideal Temperature
The temperature of both the bonnet and stickers should be between 15°C and 25°C. Avoid applying in direct sunlight or cold conditions:

Too cold: Stickers may tear or fail to adhere properly.
Too hot: Vinyl may become too soft and stretch or distort.

If needed, move the bonnet into a heated workspace to maintain a stable temperature.

Applying the Stickers
Two Application Methods: Wet or Dry

Dry Method
Use masking tape to position the sticker according to your reference notes.
Peel back about an inch of the backing paper.
Using an applicator (a credit card wrapped in a soft cloth works well), press the exposed section of vinyl onto the bonnet, pushing air outwards.
Remove the masking tape.
Gradually peel away the backing paper, keeping the loose part of the sticker under gentle tension and just above the surface. Do not remove the full backing at once—it can cause creases or misalignment.

Wet Method
Mix water with a small amount of washing-up liquid (approx. 5%) in a spray bottle.
Lightly mist the bonnet area to create a thin film.
Apply the sticker without masking tape, using the moisture to slide it into position.
Use your applicator to press out the water from the centre toward the edges.
Allow the sticker to dry for at least 24 hours before driving the tractor to prevent it from shifting due to vibration.

Note: Avoid applying stickers with the wet method on hot surfaces—the soapy water will evaporate too quickly, reducing positioning time.

Stickers with Application Tape
On David Brown models from 1974 to 1980, bonnet stickers are cut-letter vinyls rather than printed panels. These use application tape (similar to masking tape) to maintain correct positioning during application.

Apply these using the dry method only.
Once in place, press down firmly to ensure adhesion.
Carefully peel away the application tape, leaving only the lettering on the bonnet.

Helpful Tips
Store stickers in a dry place; roll longer stickers loosely to prevent creasing.
Allow stickers and bonnet to warm naturally to room temperature—do not use direct heat.
Never apply cold stickers to cold surfaces.
For large stickers, never remove all of the backing at once—work gradually.

Troubleshooting

Air bubbles?
Use a fine needle to puncture the centre of the bubble and press the air outwards using your applicator.

Caring for Your Stickers
Avoid pressure washing or steam cleaning near stickers.
Wash by hand with warm water and a mild car shampoo.
Use a soft sponge rather than brushes, which may cause scratches.

This guide is designed to help you achieve a clean, professional finish when applying new bonnet stickers. Patience and preparation are key—take your time, and you’ll get great results.

Question 6

WHERE DO I FIND THE SERIAL NUMBER?

Accepted Answer

On the Cropmaster, 25, and 30 models, serial numbers were not stamped directly into the castings. Instead, raised date-coded letters and numbers were typically found underneath the gearbox housing. More commonly, serial numbers were stamped onto an identification plate located on the dashboard panel. If this plate is missing, accurately determining the serial number can be difficult.

The practice of stamping serial numbers directly into the castings began with the introduction of the 900 series. From that point, the serial number was stamped into the horizontal section of the front casting (often referred to as the “tombstone”), just behind where the radiator mounts, or slightly to the rear of the bonnet side panel. This method continued across the Implematic, Selectamatic, and the 9, 12, and 14 series tractors.

On 90 series tractors, the serial number is stamped on the top of the engine chassis casting, directly below the lift pump.

For engine identification:
On 3-cylinder engines, the engine number is stamped approximately halfway up the block, behind the drive connection for the rev counter cable.
On 4-cylinder engines, the number is stamped at the front of the block, just below the dynamo or alternator.

The engine designation begins with a code such as AK/4 or AD/4, which identifies the engine type. For 3-cylinder engines, the designation typically begins with 55/1. The numbers following this prefix represent the individual engine serial number.

With thanks to Powerrabbit for providing this detailed information.

Question 7

BLEEDING THE HYDRAULIC SYSTEM

Accepted Answer

Based on several discussions on the forum, it appears that many members experience hydraulic lift issues—particularly after an oil change. Often, these problems are not due to mechanical faults or valve chest issues, but rather the presence of air in the hydraulic system. The following guidance can help avoid unnecessary dismantling by properly bleeding the system.

Background
On Livedrive models, the hydraulic pump operates continuously as soon as the engine starts. Because there’s a delay before the new oil reaches and circulates through the pump, this is the moment when air may be drawn into the system—causing erratic lift function.

Recommended Bleeding Procedure (After Oil and Filter Change)
Start the engine and run it at approximately 1000 RPM with the hydraulic lever in the fully lowered position.

Locate the hexagon plug on the top of the casting often referred to as the "camel’s hump"—this is the rearmost plug on the highest part of the casting between the quadrant and the seat, on top of the rear axle.

With the engine running, raise the hydraulic lever fully to the rear until oil (free of air) begins to flow from the plug. Once the oil runs clear, re-tighten the hexagon plug.

Move the lever back to the hold position (midway on the quadrant).

Locate the bleed nipple (it resembles a large grease nipple) positioned behind the 3-way valve unit, on the clutch pedal side of the tractor. This nipple can often be obscured by dirt as it sits in a recessed area facing forward, where the axle casting curves downward into the valve block.

Slacken the nipple slightly and again raise the hydraulic lever until oil flows without air. Once the oil runs clear, tighten the nipple before releasing the lever.

In some cases, the process may need to be repeated if there is a significant amount of air in the system, but usually, one careful cycle is sufficient to restore normal operation.

With thanks to Powerrabbitt for the valuable contribution.

Question 8

WIRING DIAGRAMS

Accepted Answer

885 PAGE 1

885 PAGE 2

1200

1490 & 1690

Question 9

ROTARY FUEL PUMP

Accepted Answer

Explanation provided by DBTC member “Erkki”

At the core of the rotary fuel pump is the rotor and rotor housing (part 39). The rotor operates similarly to a distributor in a petrol engine. It rotates within the housing, which has ports aligned with each injector line. When the hole in the rotor aligns with the corresponding hole in the housing, fuel is delivered to the appropriate injector.

Located above the rotor are two rollers, positioned opposite each other. Between these rollers are bearing plates, and beneath them sit two high-pressure pistons that move toward and away from each other inside a bore within the rotor.

The rollers move along a cam ring (part 57). On the smooth sections of the cam ring, the rollers are farther apart, allowing the pistons to draw in fuel. As the rotor continues to turn, the rollers reach raised cam lobes. When they pass over these lobes, they are forced inward, pushing the pistons together. This compresses the fuel between them, generating high pressure, and sends a fuel charge to the injector line.

To allow the pistons to move apart on the smooth part of the cam ring, the pump requires an internal pressure, known as interpressure, within the housing. This is generated by a vane-type (cross-blade) pump located at the rear of the injection pump. The blades (part 34) rotate inside housing 36, which is slightly off-centre relative to the rotor shaft. This eccentricity causes the blades to slide in and out of their slots, creating fuel flow and internal pressure.

Interpressure is regulated by a mechanical valve (part 18A), ensuring it stays within the correct limits.

The throttle control is managed by a small rotary valve (part 182). This valve regulates how much interpressure reaches the high-pressure side of the system. In one extreme position, it blocks the pressure entirely; in the other, it allows full flow. Between these extremes, it adjusts the amount of fuel delivered—this is controlled by the throttle pedal and a mechanical governor located at the front end of the rotor.

Question 10

TRACTOR REGISTRATION AND LOG BOOK

Accepted Answer

If you are a member of DBTC, have a tractor and don’t know the original registration number, the Club may be able to help.

Please get in touch with David Throup/Jack Beevers who will assist you in the process at :

tractor-registration@dbtc.co.uk

Question 11

PRIVACY POLICY

Accepted Answer

At David Brown Tractor Club, we appreciate that your trust is essential when handling your personal information. We are committed to maintaining the highest standards of data privacy and will only use your information for clearly defined purposes, in line with your data protection rights.

Changes to This Privacy Policy
We may update or amend this privacy policy occasionally. If we make any changes, we will notify you. Where changes significantly affect the way your data is processed or impact your rights, we will provide you with sufficient advance notice so you can exercise any applicable rights under local law (such as objecting to certain processing).

How We Collect Your Personal Information
We mainly collect your information in the following ways:
When you contact us directly via our website to request details about our products or services.
When you purchase a product.
If you provide information on behalf of someone else, you must ensure they have been made aware of this privacy policy before sharing their details.
If you are under 16 years old, please do not provide us with any personal information unless you have permission from a parent or guardian.

Please help us keep your details up to date by informing us of any changes to your contact information or preferences. You can update your preferences by emailing admin@dbtc.co.uk.

What Information We May Collect
We may collect the following personal data about you:

Name

Address

Telephone numbers

Email address

How We Use Your Personal Information
Under UK and EU data protection laws, the use of your personal data must be justified by a lawful basis, which we explain below. The main purposes for which we use your data are:

To provide customer support and respond to your enquiries.
To manage your membership, purchases, and services.
To create a customer profile using the details and preferences you provide, ensuring you receive relevant communications.
To notify you about issues related to your membership or services.
To comply with legal obligations, such as requests from law enforcement or regulatory bodies.

Use of Third Parties
We will not transfer your personal data to third parties except where required by law or legal request as noted above.

How We Keep Your Personal Information Safe
We implement a range of security measures to protect your data, including:

Restricting access to your personal data strictly on a need-to-know basis and for legitimate purposes only.
Transferring data securely by hand or email only when necessary.
Not storing highly sensitive information such as credit card details.
Using password-protected IT systems to prevent unauthorised access.
Regularly monitoring system access to detect and prevent misuse of data.

Although no method of transmission over the internet or electronic storage is completely secure, we take all reasonable steps to safeguard your information in line with applicable data protection laws.

How Long We Keep Your Information
We only retain your personal data for as long as necessary to fulfil the purposes for which it was collected and any related lawful uses. If your data is used for multiple purposes, we keep it until the longest retention period expires, stopping use for shorter purposes once their retention time ends.

Access to your data is limited to those who require it to perform their role. When no longer needed, data is either securely destroyed or irreversibly anonymised.

How to Change Your Privacy Preferences
You may update or withdraw your consent regarding how we use your personal information by:

Requesting details of the data we hold about you, or asking us to correct, delete, or restrict its use.

Emailing admin@dbtc.co.uk

Writing to:
DBTC
P.O. Box 990
Holmfirth
West Yorkshire
HD9 1YH

Contacting Us About This Policy
If you have any questions about this privacy policy or how we use your information, please contact us by:

Email: admin@dbtc.co.uk

Post:
DBTC
P.O. Box 990
Holmfirth
West Yorkshire
HD9 1YH

Your Rights
Under certain conditions, you have the right to:

Request more details about how we use your information.
Receive a copy of your personal data.
Correct inaccuracies in your information.
Request deletion of data we no longer have a lawful reason to use.
Opt out of direct marketing communications.
Receive your personal data in a portable, electronic format.
Restrict our processing of your data.

These rights are subject to certain exemptions to protect public interests (e.g. crime prevention), our legal privileges, and the rights of others.

FAQs

Frequently asked questions