The Caterpillar 120H motor grader was introduced in 1995 in the USA and Australia as the replacement for the Caterpillar 120G. Production began in Brazil a year later.

[edit] Features

The 120H has 3116 turbocharged engine with variable horsepower (HP) or engine power management. Variable horsepower units produce either 128 or 140 HP, while those with engine power management produce 125 or 140 flywheel horsepower (FWHP). It has an eight speeds forward, six reverse direct drive powershift transmission with electronic control. It comes standard with a PPPC hydraulic system, modified operator station, and adjusted blade positioning. It is available with integrated engine compartment doors and a contour seat.

The 120H was manufactured in the USA, with 4MK, 6NM, or 6TM serial number prefix; in Australia, with a 2AN prefix; and in Brazil, with a 5FM or 9YR. It was also manufactured with a 9FN prefix.

The 2AN and 4MK have variable horsepower. All other units have engine power management.

[edit] Modifications

Between 1995 and 1997 Caterpillar added radiator cleanout access covers and new battery boxes, and modified the fuel sending unit, beginning with 2AN00082, 5FM00550, 9YR00270, 9FN00439, 4MK00287, and 6TM00356. At the same time the 2AN, 9YR, 4MK, and 6TM units received a certificate of emissions compliance.

In 1996 all American units added extended life coolant and dual fuel filters, beginning with 4MK00216, 6NM00255, and 6TM00345.

In 1997 Cat added nylon plastic drawbar/circle wear inserts, scheduled oil sampling ports, and an optional 12-volt power port, beginning with 2AN00104, 5FM00800, 9YR00330, 9FN00471, 4MK00404, and 6TM00366. At the same time all units, except 2AN, received a standard circle drive slip clutch.

In 1999 the differential spider gear bearing material changed from aluminum bronze to manganese bronze to decrease the material transfer from the bearing to the spider leg, beginning with 2AN00161, 5FM01687, 9YR00404, 4MK00677, and 6TM00440.

A new Brazilian 120H unit was introduced in 2001; it was given a 6YN prefix.

In 2001 the fan spider was modified to improve service life, beginning with 2AN00180, 5FM02077, 9YR00473, and 4MK00830.

In 2003 Caterpillar introduced a new unit in the USA, with an ALZ prefix, and in Brazil, with a CAF prefix.

The new American and Brazilian 120H unit has a 3126B electronic engine with air-to-air aftercooling (ATAAC) producing 125 FWHP. It comes standard with a serpetine belt with automatic tensioner, a fuel water separator, enhanced vehicle styling, 500-hour oil change interval, modified remote engine oil drain, on-demand hydraulically driven “pull” fan, inside mounted air dryer, ground level fueling, left hand side centralized service access, sample ports on all systems, ground level coolant check, automotive-style fuses, electronic throttle, increased cab air flow to the windshield, electronic transmission directional solenoids, and LED stop/turn lights. They are also available with three-level variable horsepower.

In 2003 steering accumulators were added, beginning with CAF00275.

In 2004 a new unit was introduced in Australia, with a 124 prefix. It has a Cat 3126B hydraulic/electric unit injector (HEUI), three-valve engine with ADEM III (advanced digital engine management). It comes standard with electronic clutch pressure control (ECPC) transmission and electronic controls.

In 2004 a new final drive was added and preload was adjusted, beginning with 2AN00334, 5FM02753, 6YN00336, 9YR00672, and 4MK01012.

In 2005 a larger transmission filter was added, beginning with CAF00671.

In 2006 Cat modified the circle pinion, beginning with 5FM03827, CAF00685, and ALZ00200. An AccuGrade ready option became available, beginning with CAF00835.

Based on data from the sales database of Ritchie Bros. Auctioneers, it is estimated that more than 4,400 Caterpillar 120H motor graders have been produced.

Highest Serial #

9FN	00449
Australia
124	N/A
2AN	00122
Brazil
5FM	02236
6YN	00088
9YR	N/A
CAF	N/A
USA
4MK	00691
6NM	00473
6TM	00435
ALZ	N/A
Total = 4,494