Description

Caterpillar 312C/315C/320C/322C Training Manual – Factory Specs for Excavator Repair

If you’ve ever had a 320C throw a track or a 312C lose boom drift and you spent two hours chasing a valve spool that wasn’t even the problem – you know the pain. I’ve been there. That’s why I keep this manual within arm’s reach of my toolbox. This is the OEM Caterpillar training manual for the 312C, 315C, 320C, 320C U, and 322C excavators. It is not a reprint from some third-party that guessed the torque values. It’s the actual factory document used to train Cat technicians. 231 pages of dense, verified information – no filler, no fluff. You get the same procedures that Cat dealers use to bill $150 an hour.

Hydraulic System Diagnostics – Pressure Readings and Adjustments

The backbone of any excavator is the hydraulics. This manual walks you through pilot pressure checks, main relief valve settings, and pump compensator adjustments. Need the charge pressure spec for the 320C? Page 73. That’s a real number pulled straight from the Cat engineering data, not a rounded figure from a forum post. You’ll also find step-by-step procedures for spool bore measurements and seal replacement – with the actual tolerances, not a range.

What Torque Values Are Listed?

Every critical fastener on these machines has a torque spec in this manual: swing drive bolts, track adjuster locknuts, hydraulic line flange bolts, engine mounting brackets. The values are given in ft-lbs and N·m – but I always work in Imperial, and you should too. No guesswork allowed. The manual clearly labels the sequence and angle-tighten steps where required, like the track roller frame bolts on the 322C.

Engine Performance and Fuel System Coverage

The engine section covers the C6.6 and C7.1 power plants that came in these models. You get fuel injection timing, glow plug resistance specs, and the compression test procedure – including the adapter part numbers you’ll need. There’s a dedicated chapter on the fuel priming pump and how to bleed air from the high-pressure lines without damaging the injectors. This is the kind of detail that saves you an $800 tow to the dealer. For more background on how these diesel engines work, check out the Internal Combustion Engine overview on Wikipedia.

7 Systems Covered in This Training Manual

The book is organized by system: (1) Hydraulic, (2) Power Train, (3) Electrical, (4) Engine, (5) Air Conditioning, (6) Undercarriage, (7) Structural. Each section starts with a theory of operation – the kind of content you’d get in a factory classroom – then jumps straight into diagnostics. The electrical section alone has full circuit diagrams for the monitor panel, the ECM, and the joystick controller, with pin-out data that aftermarket manuals always get wrong. If you need a refresher on how the overall Automotive Industry Overview rates diagnostic accuracy, you’ll appreciate that this manual is the gold standard.

Source Validity – Why OEM Training Manuals Beat Aftermarket

I’ve seen techs burn two hours on a no-start because a third-party manual had the wrong ECM pin assignments for a 320C. That lost hour cost the shop $180 and the customer a day of downtime. This manual comes straight from Caterpillar – same print used at the Peoria training center. Every spec has a Cat part number reference. There are no round numbers, no “tighten to snug” instructions – only real factory tolerances. If you rely on this document, you will not be guessing. Period.

Audience Fit – Who Should Buy This Manual?

If you own a 312C through 322C excavator and do your own maintenance, you need this. It’s written for technicians, but the step-by-step format makes it usable for a competent DIYer who knows how to read a meter and turn a wrench. Beginners: do not skip the safety warnings. This manual has multiple pages dedicated to high-pressure oil safety, trapped air in accumulators, and lockout procedures. These are not suggestions – they are factory procedures designed to keep your hands attached to your arms.

Is this a service manual or a parts catalog?

It is a training manual. That means it covers theory, diagnostics, and repair procedures but does not include part numbers for ordering. For parts, get the Caterpillar parts book separately.

Does it cover the 315C with the long arm configuration?

Yes. The manual covers all variants of the 312C, 315C, 320C (standard and U), and 322C, including different boom and stick lengths. The hydraulic system adjustments are the same; only the cylinder stroke specs differ slightly, and those are listed in the appendix.

You have two options: keep chasing specs from forums and third-party PDFs that copy typos, or get the actual factory document. This is 231 pages of Cat-certified data. Access the Factory Manual. It will pay for itself the first time you avoid a misdiagnosis on a swing brake.