A portable teaching apparatus comprises inter­lock cancellation switches (135, 145) and at least one operating switch (200) for producing a signal which remains effective only when the interlock cancellation switch (135, 145) is depressed. A box-like body (100) with the operating switch (200) arranged on the front surface thereof include two parallel strips of apexes (133, 143) on the back side thereof. Slopes (134, 144) which steadily approach the front side and continued from the apexes (133, 143) are formed between the two strips of apexes (133, 143). The operating buttons of the interlock cancellation switches (135, 145) are mounted on the slopes (134, 144) respectively.

A hand-held power tool or a hand controlled implement having a primary control system (5; 35) by which a user controls operation of the tool or implement also has a secondary control system (14; 16) of pneumatic form. Operation of both systems must take place before the tool or implement is energised. A tool with primary (4) and secondary handles (7) has an actuator (5) for the primary system on the primary handle and an actuator (16) for the secondary system on the secondary handle. An implement with a single handle (51) has the actuators (55, 56) mounted at different locations on the single handle that are spaced apart by a distance preventing operation thereof by the same hand of a user.

Erfindungsgemäß wird eine elektrische Kontaktierungseinrichtung mit elektrischen Kontaktstellen (11) auf einem beweglichen Träger (10) und mit diesen gegenüberliegenden Festkontakten geschaffen, die nach einer Schaltbewegung des Träges (10) die Kontaktstellen (11) kontaktieren. Um mehrere galvanisch getrennte Kontakte zu schaffen, werden die Kontaktstellen (11) gegenseitig derart isoliert, dass sie zueinander und/oder zum Träger (10) unterschiedliche Potenziale ermöglichen. Des Weiteren wird eine besonders geeignete Tastatur (30) angegeben, mit mindestens einem ersten Tastenfeld (32), welchem eine derartige elektrische Kontaktierungseinrichtung zugeordnet ist, und mindestens einem zweiten Tastenfeld (31), dessen zugeordneter Taster (36) schaltblasenartig ausgeführt ist oder ein durch ein Schnappelement (38) vermitteltes Sprungschaltverhalten aufweist.

In a case where a left-hand push-button switch is ON, a second relay RL2 is electrically de-energized to open a normally close contact RL2-1 of the second relay RL2 so that a relay contact circuit RC is opened. If, in this state, a right-hand push-button switch is shifted to a second OFF state, a normally close contact R3-1 of the right-hand push-button switch is opened. Thus, a third relay RL3 is not electrically de-energized and a first and a second circuits are in cutoff until both the right-hand and the left-hand push-button switches are returned to a first OFF state.

A selector switch (10) is proposed to select or manipulate at least one function of a consumer product. The selector comprises an operating element having at least one operating area. The selector switch (10) comprises two key switches (22,24; 26,28; 30,32; 34,36) underneath the operating area to control the desired function.

The sub control panel for use in maintenance work comprises a control switch (107), enable switches (111-1, 111-2) and manipulation prohibition members (121-1, 121-2), which is so constituted that the control switch is not activated unless the enable switches are being kept ON by one hand of the operator and is prevented by the manipulation prohibition members from being manipulated by the one hand of the operator turning ON the enable switches. When the sub control panel (101) is to be used, the operator cannot help using both hands and is hindered from inserting the both hands to a driven part to be subjected to maintenance work of a machine when the machine is operating.

A deadman switch mechanism and a teaching operation panel equipped with the deadman switch mechanism, in which possibility of losing a safety function is low even if failure happens in a contact or other elements of a circuit. When an operator grips at least one of grip levers (GL1; GL2) with normal force, the grip levers turn around axes (AX4; AX5), shoulder portions (SD1; SD2) abut on slave levers (SL1; SL2) and turns the slave levers connected by a link (LK) around an axis (AX3) in the direction denoted by an arrow B, simultaneously, so that switches (SW1; SW2) are turned into an ON-state, simultaneously. Then, two circuits including those switches, respectively, output ON-signals independently and these signals are subjected to AND process, to allow the robot to operate. In an emergency, when an operator releases gripping of the grip levers (GL1; GL2), the slave levers (SL1; SL2) turn in the direction denoted by an arrow A, simultaneously, so that the switches (SW1; SW2) are brought into an OFF-state, simultaneously, and the robot stops immediately.

A control unit for a man rider crane comprising a chassis 1 movable horizontally and an operators cab 7 movable in a vertical direction relative to the chassis 1, the control unit being a pendant control 13 adapted to depend from the roof 11 of the cab and being movable between a stowed position 14 clear of an operator and a depending operative position, the control having two manually operable control members 18, 19 operable respectively to control the positioning of the crane and the operators cab relative thereto. The control members are such that movement of the cab and/or crane is possible only when the operator moves both of the control members 18, 19 from a neutral position to which the members are resilient biassed by a torsion spring 20.

A hand-held power tool or a hand controlled implement having a primary control system (5; 35) by which a user controls operation of the tool or implement also has a secondary control system (14; 16) of pneumatic form. Operation of both systems must take place before the tool or implement is energised. A tool with primary (4) and secondary handles (7) has an actuator (5) for the primary system on the primary handle and an actuator (16) for the secondary system on the secondary handle. An implement with a single handle (51) has the actuators (55, 56) mounted at different locations on the single handle that are spaced apart by a distance preventing operation thereof by the same hand of a user.