CORIOLIS FORCE

A benchtop base unit supporting a rotating arm on which a transparent water tank and counterbalance are mounted.

The water tank houses a submersible pump which produces a jet of water. The jet of water is observed to deflect when the arm rotates.

The deflection is due to the Coriolis force, a fictitious force which appears to act on objects moving within a frame of reference that is rotating.

Dials and a digital display on the base unit allow students to adjust the speed and direction of rotation, as well as the pump rate.

AIR BEARING APPARATUS

A self-contained product that shows how a self-acting gas lubricated journal bearing works. It also shows the onset of ‘whirl’.

The main part has a variable speed motor that turns a belt drive. The belt drive turns a precision bearing shaft. The shaft has a high-quality surface finish and spins inside a vertically loaded bush. A hand-operated load control and load cell allow the user to apply and measure the load on the bearing bush. The bush has pressure tappings equally spaced around its circumference. The tappings connect to a multichannel digital pressure display unit.

A Motor Drive Module allows the user to vary the bearing speed. A speed sensor and the bearing bush load cell connect to the Motor Drive Module. This module displays the bearing speed and the load measured at the load cell. Both the Motor Drive Module and the Pressure Display Module fit into an Instrument Frame that has extra space for the optional frame-mounted VDAS-F.

Both modules include sockets to connect to the optional VDAS-F. For quick and reliable tests, IMPACT can supply the optional VDAS® (Versatile Data Acquisition System). VDAS gives accurate real-time data capture, monitoring and display, calculation and charting of all important readings on a computer.

HERTZIAN CONTACT APPARATUS

The Hertzian Contact Apparatus is a self-contained and easy-to-use unit that shows the nature of contact between two surfaces. It compares experiment results with predictions based on Hertz’s original theories. This helps engineers to predict contact areas between common machined surfaces and materials, for example different types of bearings.

The apparatus has two pads with curved contact surfaces. The upper pad (made of a transparent plastic material) has a compound radii. The lower pad (made of an opaque flexible material) has a simple radius. A hand-operated hydraulic pump and cylinder force the two pads together. Students may rotate the lower pad, a pointer shows the angle of rotation. This allows a study of the effect of different relative curvatures.

A contact shape (or ‘zone’) forms between the pads. The contact zone may be circular or elliptical, depending on the relative angular position of the two pads. Supplied is a transparent scale to measure the contact shape and angle. Locknuts on the threads of the pump work to limit the maximum pressure, preventing damage to the equipment.

MICHELL PAD APPARATUS

The Department of Mechanical Engineering (Imperial College, London), created the original design for this apparatus. It mimics a tilting pad fluid-lubricated slider bearing, invented by A G M Michell.

The bench-mounting unit has an aluminium plate (pad) mounted above a continuous loop flat belt. The belt runs in an oil reservoir to provide a continuous supply of oil under the pad. This creates a pressurised film of oil between the pad and the belt.

A set of thirteen graduated tubes show the oil pressure across and along the film under the pad.

Included is a variable speed control to control the speed of the motor that turns the belt. Students vary the belt speed to find the relationship between sliding speed, oil viscosity and pressure distribution.

Two eccentric shafts hold the pad so students can adjust the angle of tilt of the pad. This helps students to find the relationship between pressure distribution and film thickness. Micrometers measure the leading and trailing edge positions of the pad.

Included with the apparatus is a container of oil and a viscometer to measure the viscosity of the oil.

JOURNAL BEARING DEMONSTRATION

This floor-standing apparatus allows students to study the performance of a journal bearing during different test conditions.

It is a plain steel shaft encased in a clear acrylic shell and directly driven by an electric motor. The bearing is freely supported on the motor shaft and sealed with a rubber diaphragm. The clearance is especially large to clearly show the oil in the bearing. Supplied with the equipment is a container of suitable oil.
A control unit adjusts the motor speed, which can run in both directions. A display shows the motor speed. An adjustable reservoir supplies oil to a low pressure region at both ends of the bearing.

The bearing contains 12 equi-spaced pressure tappings around its circumference and four additional ones along its topside and on a vertical radial plane. All are connected by light and flexible plastic tubes to the rear manometer panel, to clearly show the pressure head of oil at all 16 points at all times.
Students load the bearing by attaching weights (included) to arms connected to the bearing.

A strong steel frame with a worktop holds the bearing, the motor, the manometer panel and the control unit.