Search found 2050 matches

by erkki
Fri Apr 16, 2021 1:34 pm
Forum: David Brown Tractor Forum
Topic: 990 Selectamatic Linkage Geometry
Replies: 50
Views: 975

Re: 990 Selectamatic Linkage Geometry

I have one aftermarket top link which is about 24" long from middle of the pin to middle of the pin when the telescope is fully in turned. DB 1200 can handle all my implements fine with it. Some aftermarket top links may have too bulky link for DB:s bracket, so pay attention to that detail before pu...
by erkki
Thu Apr 15, 2021 4:49 am
Forum: David Brown Tractor Forum
Topic: 1694 ghost lift
Replies: 6
Views: 138

Re: 1694 ghost lift

I am unfortunately not familiar with lower link sensing. Its a good point of view to pay attention there also before digging out the valve chest.
by erkki
Wed Apr 14, 2021 9:48 am
Forum: David Brown Tractor Forum
Topic: 1694 ghost lift
Replies: 6
Views: 138

Re: 1694 ghost lift

Hmmm. Ghost lifting is obvious because of two reasons: 1. Restrict orfice plate has been removed from the by-pass valve. It makes oil flow through the valve plunger so high that the spring pressure is able to push it down too deep to cause lift. I have seen that happen when by-pass valve has been cl...
by erkki
Wed Apr 14, 2021 5:27 am
Forum: David Brown Tractor Forum
Topic: 990 Selectamatic Linkage Geometry
Replies: 50
Views: 975

Re: 990 Selectamatic Linkage Geometry

In the pictures I can see that lift rods are also adjusted to quite long setting. You get more lift height by adjusting them shorter so that when the harrow is on the ground, the arms are close to their lowest position. Right side can be adjusted by the crank on the top of the lift rod but the left ...
by erkki
Thu Apr 08, 2021 1:54 pm
Forum: David Brown Tractor Forum
Topic: 990 Selectamatic Linkage Geometry
Replies: 50
Views: 975

Re: 990 Selectamatic Linkage Geometry

Hmmm. A few implements have some poor matching geometry with DB rear lift and I have ,as well a few other DB drivers, made a second bracket for the top link about four...five inches below the original one. That makes the implement raise the back end higher. On the side walls of the PTO box four thre...
by erkki
Thu Apr 01, 2021 3:51 pm
Forum: David Brown Tractor Forum
Topic: 990 Selectamatic Gearbox, how noisy is too noisy?!
Replies: 29
Views: 673

Re: 990 Selectamatic Gearbox, how noisy is too noisy?!

Gentelemen, My reply was for mike_cullum just to explain a few things: Straight cut box is not very noisy when its ok. It becomes noisy because of abuse. The worst and most common abuse is to grind H-L area gears. In DB noise is not very worrying if the gears are not extremely worn on the face surfa...
by erkki
Tue Mar 30, 2021 9:06 am
Forum: David Brown Tractor Forum
Topic: 990 Selectamatic Gearbox, how noisy is too noisy?!
Replies: 29
Views: 673

Re: 990 Selectamatic Gearbox, how noisy is too noisy?!

Hmmmm. DB transmission is not noisy when new and the reason for whine of older tractors' gearboxes is surface damages of the gears face surfaces due to crunchy engage, especially when changing when tractor moving. Its high-low areal gear pairs which produce most noise because they are running on hig...
by erkki
Sun Mar 14, 2021 10:50 am
Forum: David Brown Tractor Forum
Topic: 1390 Mechanic?
Replies: 17
Views: 665

Re: 1390 Mechanic?

If the tractor has three way valve it is a pretty simple task to make quick drop function for empty arms: Connect one end of a pipe or a hose to the three way valve port "1" and the other end to the return line. Now, when you click the three way valve to "1/L" position the arms drop pretty quickly. ...
by erkki
Fri Mar 05, 2021 5:33 pm
Forum: David Brown Tractor Forum
Topic: 770 selectamatic lift capacity with pallet tines on linkage
Replies: 4
Views: 185

Re: 770 selectamatic lift capacity with pallet tines on linkage

Sorry, I have no personal experience of 770 but I have transported LOTS of firewood on three point lift assembled box. 880 selectamatic without extra front end weight is able to handle close to 2 cubic metres of fresh birch, but only on hard yard. Then the front wheels are touching ground only very ...
by erkki
Mon Feb 22, 2021 5:21 pm
Forum: David Brown Tractor Forum
Topic: David Brown 996 hydraulic issue
Replies: 32
Views: 840

Re: David Brown 996 hydraulic issue

Outch, Very odd symptoms. Now the ram is fully isolated from the valve chest, so there are not many possible sources of a leak. Try this: When lifting requires full revs to lift a bale, when the bale comes up, turn the three way valve one click left and see what happens. If the ram leaks or if the p...
by erkki
Mon Feb 22, 2021 1:36 pm
Forum: David Brown Tractor Forum
Topic: Cylinderhead Identification
Replies: 2
Views: 181

Re: Cylinderhead Identification

Hmmmm. The outlook of cyl. heads of 4/47, 4/49 and 4/55 is very alike. Actually, 4/47 head may work fine with all those engines but probably not vice versa. The valves are probably bigger in 100 m bore engines but I cant see a reason why the big bore engine would not run by smaller valves. Power out...
by erkki
Mon Feb 22, 2021 1:20 pm
Forum: David Brown Tractor Forum
Topic: David Brown 996 hydraulic issue
Replies: 32
Views: 840

Re: David Brown 996 hydraulic issue

Sticky by-pass valve and hold-release valve can be cured by polishing the plungers. Some wear of the diameter and clean surface will do the trick. Clean oil is essential also. In this 996 case I suspect that if the modified system has been working well for years, an accidental moving of the main con...
by erkki
Sun Feb 21, 2021 5:11 pm
Forum: David Brown Tractor Forum
Topic: David Brown 996 hydraulic issue
Replies: 32
Views: 840

Re: David Brown 996 hydraulic issue

Hmmmm. If the three way valve is not isolated from the valve chest, the system will lose pressure through the hold-release valve if the rear lift control lever is not back. If the hold-relase valve is stuck open, try turning the lowering speed control knob fully in so you will see if there is any di...
by erkki
Sun Feb 21, 2021 9:42 am
Forum: David Brown Tractor Forum
Topic: David Brown 996 hydraulic issue
Replies: 32
Views: 840

Re: David Brown 996 hydraulic issue

Hmmm. The key question is if the arms are up or down. If they are stuck up, the problem may be the mechanical lock on the LHS of the cross shaft. If the arms are down, the problem can be mechanical. I have seen a broken piston in the lift ram. There was a brittle fracture in the groove of the 0-ring...
by erkki
Fri Jan 22, 2021 5:55 am
Forum: David Brown Tractor Forum
Topic: 990 water in oil
Replies: 6
Views: 444

Re: 990 water in oil

i have seen a 880 selectamatic from 1967 which had corroded block. The tractor had been running just short times in summer time and the coolant had been water all those years. The owner of the tractor started restoration and soon faced the problem of milky engine oil. The block had needle pin size l...