JACOBS ENEGINE BRAKE INSTALLATION MANUAL FOR MODEL C-346B Caterpillar

Section 1 Introduction

Usage:

Table 1 - Master-Slave Circuit Relationship Listed In Engine Firing Order

THEORY OF OPERATION - Simply stated, energizing the Engine Brake effectively converts a power producing diesel engine into a power absorbing air compressor. This is accomplished when desired by motion transfer through a master-slave piston arrangement which opens the cylinder exhaust valves near the top of the normal compression stroke releasing the compressed cylinder charge to exhaust.

The blowdown of compressed air to atmospheric pressure prevents the return of energy to the engine piston on the expansion stroke, the effect being a net energy loss since the work done in compressing the cylinder charge is not returned during the expansion process.

Exhaust blowdown of the braking cylinder is accomplished by utilizing the push rod motion of an exhaust valve of another cylinder during its normal exhaust cycle as follows:

1. Energizing the solenoid valve permits engine lube oil to flow under pressure through the control valve to both the master piston and the slave piston.

2. Oil pressure causes the master piston to move down, coming to rest on the corresponding exhaust rocker arm adjusting screw. (See Table No. 1 for master-slave operating relationship.)

3. The Exhaust rocker pushrod begins upward travel (as in normal exhaust cycle) forcing the master piston upward and creating a high pressure oil flow to the slave piston braking cylinder. The ball check valve in the control valve traps high pressure oil in the master-slave piston system.

4. The slave piston under the influence of the high pressure oil flow moves down, momentarily opening the exhaust valve while the engine piston is near its top dead center position, releasing compressed cylinder air to the exhaust manifold.

5. Compressed air escapes to atmosphere completing a compression braking cycle.

Method Of Driving A Vehicle Equipped With A Jacobs Engine Brake

It is easy to learn the proper method of driving a vehicle that's equipped with a Jacobs Engine Brake. Since the engine brake is most effective at higher engine speeds, gear selection is very important. Gearing down the vehicle within the limits of recommended engine speed makes the engine brake a more effective retarder. Maximum retarding occurs with the selection of the lowest gear that prevents exceeding the maximum allowable engine speed.

The Model C-346 Series Engine Brake kits contain a progressive switch that provides three- or six-cylinder operation with greater flexibility in selecting the amount of retarding needed for various road conditions.

For more information on driving with the Jake Brake, consult your owners' Driver's Manual. To get a detailed presentation on driving with the Jacobs Engine Brake, consult your Jacobs Distributor.

Model Number Identification And Engine Brake Housing Part Number Identification

Each C-346B engine brake housing assembly has an identification plate showing model number and part number.

Model numbers for C-346A and C-346 housings can be found stamped in the casting.

Engine Brake Housing Serial Number

The brake housing serial number is located on the brake housing. This Installation Manual should be used in conjunction with Jacobs Parts Manual when replacement part information is required. The Parts Manual can be obtained from your Jacobs distributor.

Engine Model Identification

Prior to engine brake installation, check engine model number. Verify that engine model is correct for engine brake model being installed. The engine model identification is on the serial number plate shown above and below. Engines prior to serial number 7FB39279 require leveling shims. See Alternate Housing Installation Procedure on page 18.

7FB Serial Number Prefix is 3406B Engine, 92U Serial Number Prefix is Earlier 3406 Engine, 3406-3406B Engine identification is by Serial Number prefix.

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NOTICE

DO NOT USE MODEL C-346 OR MODEL C-346A ON 3406B ENGINES. 3406B ENGINE IDENTIFICATION IS ESSENTIAL TO PREVENT MISMATCH OF ENGINE BRAKE AND ENGINE. OPERATION OF MODEL C-346 OR C-346A ENGINE BRAKE ON 3406B ENGINE WILL RESULT IN ENGINE DAMAGE.