Hand-Lever Controls

Presses dedicated to die spotting are used primarily by die shops or large stamping facilities they are included here because they can have specialized features. Because they are used to spot dies, these presses require precise control over the movement of the slide. The operator usually controls the slide movement in a manual mode by means of a hand lever. Speed is variable and typically slow when compared with production presses. The slide should be well guided for precise alignment and parallelism. 

Don t use hand lever to apply only trailer brakes. You could overheat trailer brakes and not have enough capacity in tractor to control speed adequately. 

The control shaft is rotated with the help of a hand-lever which engages with a latch in a number of registers on a graduated arc. The various positions of the hand-lever are given by the valve-lift diagram the maximum angular displacement is about 75°. 

The larger the cross-section of the valves the more increase the resistance met by the stem and the power required to actuate the hand-lever. With heavy presses it is therefore impossible for the operator to turn the control shaft directly with the help of a hand-lever. In such cases the con-... 

The various hand-lever controls for tube and rod extrusion presses are arranged in such a way that the operator can closely watch the ram motions and the charging operations. A drawback to this system is the large space required and the distances between the various hand-levers, on account of which the operator has to change his position frequently... 

It is for these reasons that - already many years ago - the controls were installed underground (Fig. 180), that the hand-levers were arranged closely to each other and that these were connected to the control shafts via a mechanical or hydraulic linkage. This development and the demand for automation of the working operations soon led to electric remote drives (Fig. 181) being actuated by pushbuttons or small control levers from a central desk. These drives operate directly or via a servo-motor, as already described, the control shaft. 

As long as the potentiometer bridge remains in electrical equilibrium, the electric drive of the control shaft has no reason to perform a rotation. However, as soon as the hand-lever of the control potentiometer is moved in any direction thus disturbing the equilibrium, the potential difference of the potentiometer bridge releases an electric control pulse, which is amplified by electronic tubes and transmitted to the motor contactors. Through a gear the drive motor rotates the control shaft in the desired direction, while the contact lever which scans the compensation potentiometer, joins in this motion. Thus an equilibrium is re-established on the... 

In subsequent years, Savery made important improvements that benefited future steam inventions. In June 1699 he demonstrated to the Royal Society a pump with two receivers, each with a separate, hand-controlled steam supply. This ensured improved continuity of operation, allowing one receiver tn operate in its vacuum stage and the other under steam pressure. In 1701, he added two more critical steps a second boiler, avoiding the need to shut down the fire and pump, between stages and he replaced the two interconnected steam cocks with a single valve, run with a manually operated long lever. This may have been the inspiration for the modern slide valve and his inventiveness created, in effect, the world s first feed-water heater. 

Most of these devices are actually made rather simply, in that there is a particular cable, like a marionette string, that goes directly from the controls to the hands. But, of course, things also have been made using servo motors, so that the connection between the one thing and the other is electrical rather than mechanical. When you turn the levers, they turn a servo motor, and it changes the electrical currents in the wires, which repositions a motor at the other end. 

Many hand controls are attached to the steering column. Hand-controls either clamp to the steering column or are attached to a bracket which is bolted to the steering column or dash, typically where the steering column bolts to the dash. Installation of the hand-controls should not interfere with driver safety features (e.g., air bags, collapsible steering columns). The push rods of the hand-control either clamp directly to the pedals or the levers connected to them. 

It is probable that all heavy matter possesses—latent and bound up with the structure of the atom—a similar quantity of energy to that possessed by radium. If it could be tapped and controlled what an agent it would be in shaping the world s destiny The man who put his hand on the lever by which a parsimonious nature regulates so jealously the output of this store of energy would possess a weapon by which he could destroy the earth if he chose. 

There was a box supporting four levers for controlling the bucket. Hoses from the hydraulic pump entered and left the sides of the box. The hoses were fabric-reinforced hoses. The hoses were about 4 inches from the operator s hand when positioned on the levers. One hose created a very fine stream of hydraulic fluid when it started to fad. The stream sprayed directly to the normal hand position. 

The 10 1 cantilever arm is loaded with a variety of stacked weights shown in Fig. 13.14c. By requiring only one-tenth of the actual stretching force applied at the free end of the tensile specimens at the other end of the lever arm, this mechanical advantage permits easy application of loads by hand. The test temperature was precisely controlled at 50-80°C in an efficient air-heated chamber shown in Fig. 13.14b. 

Equipment must be accessible and easy to operate, even if the victim has impaired vision. Hand-pull levers, panic bars or walk-on foot controls can be used to operate a stay-open ball valve to deliver a continuous drench for the ANSI reconunended 15 minutes. The casualty must be able to remove contaminated clothing without having to hold on to a spring return valve. 

Control and Operation. A continuum of robotic control systems ranges from fiilly manual operation to fully autonomous operation. On the one hand, a human operator may be required to direct every movement a robot makes. For example, some bomb disposal robots are controlled by human operators working only a few feet away, using levers and buttons to guide the robots as they pick up and remove the bombs. On the other side of the spectrum are... 

Keep feet and legs inside the operator s cab or guards do not put any part of the body through the uprights of the truck keep hands where they cannot be pinched between steering or control levers and stationary objects in tight spaces. 

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