Abstract: A pallet truck including a controller that calculates the height of the fork carriage without the use of mechanical devices such as switches or sensors. A calculated carriage height is derived by adding the amount of time that a carriage is commanded to be raised and offsetting that by the amount of time that the carriage lower button is depressed. The calculated carriage height is essentially an accumulated lift time where the time that the carriage is lifting is a positive value and the time that the carriage is lowering is a negative value. When these values are combined, the result is the present calculated carriage height. The controller further monitors the calculated carriage height such that if the carriage is too close to the ground, the maximum speed of the pallet truck is limited to prevent damage to the forks or ground due to striking or scraping between them.

Abstract: A pallet truck including a controller that calculates the height of the fork carriage without the use of mechanical devices such as switches or sensors. A calculated carriage height is derived by adding the amount of time that a carriage is commanded to be raised and offsetting that by the amount of time that the carriage lower button is depressed. The calculated carriage height is essentially an accumulated lift time where the time that the carriage is lifting is a positive value and the time that the carriage is lowering is a negative value. When these values are combined, the result is the present calculated carriage height. The controller further monitors the calculated carriage height such that if the carriage is too close to the ground, the maximum speed of the pallet truck is limited to prevent damage to the forks or ground due to striking or scraping between them.

Abstract: An enclosure for electronic circuitry includes a container that is formed to define an enclosed volume. An open end of the container is sealed by a printed circuit board which also provides electrical connection to the enclosed electronic circuitry by means of connectors mounted to its inside and outside surface.

Abstract: A method for monitoring the temperature of a friction brake to prevent overheating of the brake is disclosed. The vehicle speed and brake activation time are monitored for braking event conditions known to add heat to the brake or brakes, and the frequency or rate of occurrence of these conditions is monitored. When the frequency of brake event conditions approaches a threshold value known to be approaching an over-temperature condition, the speed of the vehicle is limited in order to limit the amount of kinetic energy which can be absorbed by the brakes, thereby preventing the brakes from overheating.

Abstract: A state-of-charge indicator system monitors the battery current and voltage during operation of a lift truck. Selected current and voltage samples are used to calculate the internal battery resistance and this is employed to calculate a “dynamic” battery voltage. This dynamic battery voltage is used as input to a stored look-up table which provides a battery state-of-charge value.

Abstract: A method and/or apparatus for reducing the maximum speed of a lift truck when a fork carriage exceeds a fork carriage trip height and a limit switch positioned at the trip height to detect trip height has failed. Using lift truck control signals, a calculated fork carriage height is determined and compared to the trip height which corresponds to the limit switch position. When the calculated height reaches the trip height and the limit switch does not provide a sensed signal, a latch is set in a non-volatile memory which limits the maximum truck speed until the limit switch is again operable.