A single-wire safety system is provided that yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay acting as a communications master device and one or more safety devices connected in series with the safety relay via a single-wire communication circuit. A smart tap device is used to interface safety devices that are not compliant with the single-wire protocol to the single-wire channel. The safety device or smart tap device farthest from the safety relay on the safety circuit modulates a safety signal with a recognizable pulse pattern that traverses the single-wire safety circuit to the safety relay via the intermediate safety devices or smart taps. The safety relay maintains safety mode as long as the pulse pattern is received and recognized. The architecture allows bi-directional communication of initialization, configuration, and diagnostic messages over the single-wire safety channel.

A single-wire safety system architecture is provided that yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay acting as a communications master device and one or more compatible safety devices connected in series with the safety relay via a single-wire communication circuit. The safety device farthest from the safety relay on the safety circuit modulates a safety signal with a recognizable pulse pattern that traverses the single-wire safety circuit to the safety relay via the intermediate safety devices. The safety relay maintains safety mode as long as the pulse pattern is received and recognized. The architecture allows bi-directional communication of initialization, configuration, and diagnostic messages over the single-wire safety channel, and can also allow safety devices to insert prognostic data into the safety signal in order to convey health information while the system is in normal operation mode.

A protective system for an electric unit operated by an installable battery pack includes: a control device configured to activate the electric unit in the case of the installed battery pack by operating a main switch; a contact device of the electric unit and a contact device of the battery pack including mutually complementary contact elements, which in each case form a first and a second interface for producing a first and a second electrical connection between the electric unit and the battery pack. In this instance, the contact devices are configured, during the installing of the battery pack, to produce the first electrical connection before the second electrical connection in time.

A battery system includes a battery cover, a battery access panel removably connected to the battery cover, and a service disconnect switch. The service disconnect switch includes an electrical interlock switch. The service disconnect switch has a first position cooperating with the battery access panel to prevent removal of the access panel from the battery cover. In the first position, the service disconnect connects a traction battery to circuitry. The service disconnect also has a second position, the second position being displaced from the access panel and disconnecting the battery.

A handheld work apparatus has a device for starting an electric drive motor via an actuating element which can be displaced in a handle counter to an actuating force and acts on a transmission element. The transmission element is shiftable from a rest position into an operating range, wherein the transmission element actuates a switching element and starts the motor. For shifting from the rest position into an end position, a shift force is applied. The shift force forms at least a portion of the actuating force. To keep the actuating force low after the motor is switched on, the displacement path of the transmission element is divided into a first segment and a second segment which includes the operating range. The shift force to be applied to the transmission element rises on the first segment of the path and, after a maximum, decreases on the second segment.

A handheld work apparatus has a device for starting an electric drive motor via an actuating element which can be displaced in a handle counter to an actuating force and acts on a transmission element. The transmission element is shiftable from a rest position into an operating range, wherein the transmission element actuates a switching element and starts the motor. For shifting from the rest position into an end position, a shift force is applied. The shift force forms at least a portion of the actuating force. To keep the actuating force low after the motor is switched on, the displacement path of the transmission element is divided into a first segment and a second segment which includes the operating range. The shift force to be applied to the transmission element rises on the first segment of the path and, after a maximum, decreases on the second segment.

Production and work machines are to be able to be more safely operated. Thereto, they can be equipped with a safety device, which comprises a light curtain, a first and a second reflection device, which are each formed for reflecting light of the light curtain, and a first identification element integrated in the first reflection device as well as a second identification element integrated in the second reflection device. Moreover, the safety device comprises a first sensor device and a second sensor device for reading out the identification elements. A control device provides a start signal for the machine only if the first sensor device reads out the first identification information and the second sensor device reads out the second identification information at the same time.

Production and work machines are to be able to be more safely operated. Thereto, they can be equipped with a safety device, which comprises a light curtain, a first and a second reflection device, which are each formed for reflecting light of the light curtain, and a first identification element integrated in the first reflection device as well as a second identification element integrated in the second reflection device. Moreover, the safety device comprises a first sensor device and a second sensor device for reading out the identification elements. A control device provides a start signal for the machine only if the first sensor device reads out the first identification information and the second sensor device reads out the second identification information at the same time.

A chainsaw includes a handle with a handgrip; an electric motor for endlessly moving a saw chain; a control unit for controlling rotation of the motor; and a main power switch switchable between an ON state and an OFF state. The handgrip is provided with a gripping detection device for detecting whether the handgrip is gripped by the worker, and the chainsaw is configured to, when the control unit is manipulated to deactivate the electric motor in a state in which the gripping detection device detects that the handgrip is gripped, maintain the main power switch in the ON state, and to, when the control unit is manipulated to deactivate the electric motor in a state in which the gripping detection device detects that the handgrip is not gripped, switch the main power switch to the OFF state.

A chainsaw includes a handle with a handgrip; an electric motor for endlessly moving a saw chain; a control unit for controlling rotation of the motor; and a main power switch switchable between an ON state and an OFF state. The handgrip is provided with a gripping detection device for detecting whether the handgrip is gripped by the worker, and the chainsaw is configured to, when the control unit is manipulated to deactivate the electric motor in a state in which the gripping detection device detects that the handgrip is gripped, maintain the main power switch in the ON state, and to, when the control unit is manipulated to deactivate the electric motor in a state in which the gripping detection device detects that the handgrip is not gripped, switch the main power switch to the OFF state.