Engine body Design

And Function

The engines are in-line, 6-cylinder, 4-stroke, diesel engines with direct injection. The engines are designed with oil cooled pistons and wet, replaceable cylinder liners, separate cylinder heads, one for each cylinder and exhaust driven turbo chargers.

TAD-engines are equipped with an intercooler, located behind the radiator and cooled by air via a thrust type of fan. TWD-engines are equipped with an intercooler, cooled by water.

TWD1230ME has two-piece articulated pistons. The crown of the piston is made of nodular iron while the skirt is made of aluminium. Each section is journaled separately in the gudgeon pin.

Nitro-carburated timing gears

General instructions for the replacement to nitro-carburated timing gears

When changing to nitro-carburated timing gears, only the following drive combinations should be used:

● Nitro-carburated drive (marked N or NITRO) must never run against an induction hardened drive (marked HT).

● An exception to this rule, however, is the gear for the coolant pump on the 121 series engines. The coolant pump’s drive (5, fig on next page) and the intermediate gear (4) for the same, which both are nitro-carburated, may run against the injection pump’s drive (3), which was induction hardened in the earlier version.

● Case hardened gears (marked CH) are permitted in all gear combinations.

To recognize nitro-carburated gear, the following applies:

● Nitro-carburated gears are easily recognized by their matt grey to grey/yellow colour. For a transition period they will also be marked with white oilresistant paint, and later an “N” or “NITRO” will be punched in the gear (please refer to the illustrations on this page).

Note! For a transition period (approx. 3 months), engines with nitrocarburized timing gears will be marked with a yellow paint dot on the timing gear casing above the “compressor cover” (timing gear casing’s rear edge, right hand side).

Marking of gears

Nitro

N=Nitro-carbonated

HT=Induction hardened

CH=Case hardened or marked with white oil-resistant paint in early versions

Engine body - Design and function

Instructions for production engines

The following figures and tables show from which engines numbers that nitro-carburated timing gears have been introduced in production. Part numbers are also stated for drives of later and earlier versions.

Marking of gears

N=Nitro-carbonated

HT=Induction hardened

CH=Case hardened Engines in 100 and 121 series

Up to and incl. engine No.From engine No.

100-serien: xxxx/220979100-serien: xxxx/220980

121-serien: xxxx/155515121-serien: xxxx/155516

Pos.Timing gear

VersionVersion

1Crankshaft gearCHCH

2Intermediate gearCHCH

3Injection pumpHTN

4Hydraulic pump (100-series)HTN Interm. gear (121-series)NN

5Coolant pump (121-series)NN

6Hydraulic pump (121-series)HTN

7CamshaftHTN

8Compressed air compressorHTN

Instructions for factory overhauled engines

For engines overhauled at the factory, the production marking of the nitro-carburated timing gears may disappear. The existing designation plate on factory overhauled exchange engines will therefore be altered in accordance with Fig. 8 below. The earlier marking “CYLINDER DIM.” has been changed to “TIMING GEAR”. The corresponding box will have the text “NITRO” for engines fitted with nitro-carburated drives, and “HT” for engines with induction drives.

NOTE! It is important to check for information on this plate after replacement or before fitting of a compressed air compressor or servo pump to a factory overhauled engine, to make sure which type of timing gear has been fitted at overhaul.

Crankshaft

The crankshaft is nitro-carburized. A nitro-carburized crankshaft has a greater resistance to fatigue and wear than an induction-hardened crankshaft.