1981/02/04 Caterpillar

All Caterpillar Engines

Some components of the 4S6553 Engine Evaluation Test Instrument Group have not been regularly available. Because of this, the 4S6553 Group has been canceled and replaced by the 6V3150 Engine Pressure Group and 6V3121 Multitach Group.

6V3150 Engine Pressure Group

The 6V3150 Engine Pressure Group can be used with the 6V3121 Multitach Group to make an analysis of engine performance in diesel and natural gas engines and to make operating adjustments to natural gas engines.

Illustration 1. The 6V3150 Engine Pressure Group.

Components of the 6V3150 Engine Pressure Group are shown in the chart.

The 6V3150 Engine Pressure Group is basically the same as the former 4S6553 Engine Evaluation Group, with one difference: the tachometer is now a separate tool. (See the topic "6V3121 Multitach Group".) The 6V3150 Engine Pressure Group has six gauges. The 6V4018 Gauge is the low pressure gauge used to measure pressures of 0 to 400 kPa (0 to 60 psi) with an accuracy of ±7 kPa (±1 psi). The 6V4016 Gauge is used for higher pressure, 0 to 1100 kPa (0 to 160 psi) with an accuracy of ±18 kPa (±3 psi).

The two 6V4017 Gauges can measure 0 to 400 kPa (0 to 60 psi) pressure above ambient pressure and 0 to 100 kPa (0 to 15 psi) vacuum. The accuracy of each gauge is ±7 kPa (±1 psi) for positive pressure and±1.5 kPa ( ±.2 psi) for vacuum. These four gauges are filled with glycerine to dampen (decrease the effect of) pressure pulses.

Illustration 2. The 6V3150 Engine Pressure Group has storage space for the 6V3121 Multitach Group.

The two 5P6579 Gauges have a range of 0 to 12 kPa (0 to 50 inches of water) and are accurate within ± .3 kPa (± 1.0 inches of water).

The 6V3150 Gauge does not include a tachometer to measure speed (R/MIN). However, it is made to provide storage space for the 6V2100 Multitach, 5P7360 Tachometer Drive Generator, 5P7362 Signal Cable and 5P7366 Power Cable (parts of 6V3121 Multitach Group). These four components, when used with the 6V3150 Group, provide the same basic functions as the former 4S6553 "Boost Kit" at a much lower cost.

The advantage of a separate tachometer is that it can be used on other jobs when it is not needed in the 6V3150 Group.

Characteristics Of The 6V3150 Engine Pressure Group:

1. It weighs 2.7 Kg (6 lb) less, without 6V2100 Multitach, than the former 4S6553 Group.

2. It comes in a green polyethylene case (plastic) to provide a cost and weight advantage and does not scratch or permanently dent.

3. It has an anodized aluminum panel.

4. It uses dual scale gauges: inches of water or psi and kPa.

5. It is one of the first of a new series of Caterpillar Diagnostic Tools. This family is easily identified by a green polyethylene case with black panels and white printing.

6. It has enough space for the storage of the new 6V2100 Multitach (part of 6V3121 Multitach Group) to give a "boost kit" assembled of modular tools.

1. Weight: 5.0Kg (11 lb), without 6V2100 Multitach.

2. Size: 39 mm × 311 mm × 101 mm (15.5 " × 12.25" × 5.50").

3. Gauge Accuracies Over Specified Operating Temperature Range:

4" diameter differential: ±2% of full scale

2 1/2" diameter single port -SAE Grade "A" (2%-1%-2%)

4. Operating Temperature Range:

4" diameter differential gauge: -1.1 to 60°C (30 to 140 °F)

2 1/2" diameter single port: -18 to 71.1°C (0 to 160°F)

5. Overrange Pressures:

4" diameter differential gauges: 15 psi

2 1/2" diameter single port gauges - pressures above full scale destroy gauge accuracy

6. Pressure Media:

4" diameter differential gauges - clean air and gases only, no fluids

2 1/2" diameter single port gauges - air, oil, water, antifreeze, diesel fuel

7. Operating Position:

4" diameter differential gauges - no effect on accuracy if pointer is mechanically adjusted to zero.

2 1/2" diameter single port gauges - no effect on accuracy

The uses of the different gauges in the 6V3150 Engine Pressure Group are listed below.

The 5P6579 Differential Gauge, 4" diameter, is used to measure:

* Crankcase Pressure

* Air Inlet Restriction

* Exhaust Restriction

* Gas Pressure for Gas Engines

The 6V4016 Gauge (0 to +160 psi), single port, is used to measure:

* Oil Pressure

* Air Compressor Cut-in and Cut-out Readings

The 6V4017 Gauge (-15 to +60 psi), single port, is used to measure:

* Inlet Manifold Pressure on Turbocharged Engines

* Manifold Vacuum on Natural Gas and Gasoline Engines

* Power Balancing of Twin Engines in a Natural Gas or Diesel Application

The 6V4018 Gauge (0 to 60 psi), single port, is used to measure:

* Fuel Pressure

* Inlet Manifold Pressure on Turbocharged Engines

* Cooling System Pressure

These uses are examples only but are not the complete list. This group is not limited to "Engines" only, but is a "low pressure" group with many field service uses.

6V3121 Multitach Group

The 6V3121 Multitach Group contains the 6V2100 Multitach and the items needed for its use.

Illustration 3. The 6V3121 Multitach Group.

The 6V2100 Multitach is a small digital tachometer that contains a microcomputer which can be programmed by the serviceman to change different input signals into an R/MIN indication which is shown on the front panel readout. It has a range of 40 to 9999 R/MIN with an accuracy of ± 1 R/MIN. Programming and control of the Multitach is done by use of the touch switches mounted on the front panel. The Multitach can be used as a remote readout phototach, or it can be used with a magnetic speed pickup or tachometer generator.

To prevent possible failures, the electronic components of the Multitach are thoroughly tested at the factory. Several tests are used, including three thermal shocks (heat stresses), and 100 hours of operation at 40 volts DC and at a temperature of 60 °C 140°F). After the tests are finished, the circuit assemblies are sealed with a plastic-like material to prevent possible corrosion or other damage.

Components of the 6V3121 Multitach Group are shown in the chart.

Illustration 4. The 6V2100 Multitach.

R/MIN READOUT: R/MIN is shown on a liquid crystal digital four digit display, in numbers 13 mm (.5 ") high. The display is visible in direct sunlight and in low light conditions.

PROGRAMMABLE: The Multitach can be programmed by using the touch switches on the front panel. The Multitach will then display R/MIN directly from an input signal with any number of P/REV (pulses per revolution) between 1 and 256. It will also directly display R/MIN with an input signal of 0.5 P/REV.

MEASUREMENT RANGE: Range of Multitach is 40 to 9999 R/MIN.

TYPE OF PICKUP: R/MIN can be measured by using either the photo pickup and retro-reflective tape, or a magnetic pickup or tachometer generator.

INPUT SENSITIVITY: The magnetic input reads signals as low as .04 volts peak. The photo pickup operates up to 90 cm (36 ") from a retro-reflective tape target.

INPUTS: Connections are provided for photo/pickup and magnetic pickup or tachometer generator. There is also a connection for power input.

INPUT SELECTION: Touch switches are used to select either photo or magnetic input. An indicator light shows which input is being used.

SIGNAL INDICATOR: An indicator light shows when no input signal is present, and flashes on and off when low R/MIN signals are present.

POWER: Power supply for the Multitach comes from an external vehicle battery or any DC voltage source from 11 to 40 volts at .3 amps. Inputs are protected against voltage surges up to 150 volts DC.

POWER POLARITY: Power input to the Multitach is not polarized. Positive or negative can be connected to either input connection.

CALIBRATION: No adjustments are necessary for accuracy, since the Multitach is designed to maintain its original accuracy for the life of the instrument. However, accuracy can be checked by using the 5P9698 Calibrator.

OVERRANGE: Overrange in either the R/MIN or P/REV mode is indicated on the digital readout by the removal of all numbers and the display of three decimal points.

P/REV IDENTIFICATION: The P/REV number which has been programmed into the Multitach can be displayed on the digital readout. When displayed, this number flashes on and off.

ACCURACY:±1 R/MIN at 40 to 9999 R/MIN with P/REV up to 50. Because of its accuracy, the Multitach can be used to correctly set speeds on excavators and the new hydrostatic drive machines, which require a speed adjustment accuracy of ±10 R/MIN. The tachometers presently used have an accuracy of ±8 R/MIN to±50 R/MIN.