“N” and “NN” TYPE INJECTION PUMPS
The pump nameplate bears a long stamping giving the pump number and also the governor number. The governor nameplate bears the governor stamping only, with the addition of a speed range symbol in the case of mechanical governors.
a) Typical stampings are NL6E80/8GRHD4C1 – NNL6E90/65MGLVW3M – NL4E75/80GRP4 – NNR6E80/74GLWA3
b) Pump stamping NNL6E80/8G
N – Basic type of pump
N – Uprated version
L – Camshaft assembly (i)
6 – No, of pumping lines
E – Design change letter
80 – Element plunger dia (ii)
/ – Dividing stroke
8 – Individual features number
G – Governor fitted (iii)
Camshaft assembly letters “L” or ’’R” indicate:
“L” – Notched end of camshaft at L.H end (when facing inspection cover)
“R” – Notched end of camshaft at R.H end (when facing inspection cover)
Looking from inspection cover side of pump
Element plunger diameters in tenths of mm
50, 60, 65, 70, 75, 80, 90 or 100
The letter “G” is not strictly part of the pump formula but is inserted to separate the pump from the governor symbol
c) Governor stampings
There are three main types of governor suitable for fitment to the “N” type pump:
hydraulic (H), pneumatic (P) and flyweight (W)
Their type formulae arc derived as follows:
d) Hydraulic Governor (for “N” pump)
A typical stamping is RHD4C1
R – L or R indicates end of pump to which governor is fitted (when facing inspection cover)
H – Governor type
D – Design change letter
4 – Individual features number
C – C – Clockwise A – Anti-clockwise (Rotation looking at driving end of pump)
1 – Test data code number
e) Pneumatic Governor (For “N” and “AA” pumps)
RPE4
R – L or R indicates end of pump to which governor is fitted (when facing inspection cover)
P – Governor type
E – Built in excess fuel device
4 – Individual features number
f) Mechanical Governor (For “N” and “AA” pumps) LWA3
L – L or R indicates end of pump to which governor is fitted (when facing inspection cover)
W – Governor type (i)
A – Design change letter
3 – Individual features number
i) “W” indicates an idling and maximum speed governor:
“VW” indicates a variable speed governor
ii) Governed speed range is quoted separately on governor type label (see notes BR and BRV governors re speed ranges)